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Reprinted . . . 1922 

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Prfotrd ** Gnat Britain *y 



THIS book has grown out of an attempt to harmonize 
two different tendencies, one in psychology, the other in 
physics, with both of which I find myself in, sympathy, 
although at first sight they might seem inconsistent. On 
the one hand, many psychologists, especially those of the 
behaviourist school, tend to adopt what is essentially a 
materialistic position, as a matter of method if not of 
metaphysics. They make psychology increasingly depen- 
dent on physiology and external observation, and tend 
to think of matter as something much more solid 
and indubitable than mind. Meanwhile the physicists, 
especially Einstein and other exponents of the theory of 
relativity, have been making " matter " less and less 
material. Their world consists of " events," from which 
*' matter " is derived by a logical construction. Whoever 
reads, for example, Professor Eddington's Space, Time and 
Gravitation (Cambridge University Press, 1920), will see 
that an old-fashioned materialism can receive no support 
from modern physics. I think that what has permanent 
value in the outlook of the behaviourists is the feeling 
that physics is the most fundamental science at present 

in existence. But this position cannot be called material- 



istic, if, as seems to be the case, physics does not assume 
the existence of matter. 

The view that seems to me to reconcile the materialistic 
tendency of psychology with the anti-materialistic ten- 
dency of physics is the view of William James and the 
American new realists, according to which the " stuff " 
of the world is neither mental nor material, but a " neutral 
stuff," out of which both are constructed. I have 
endeavoured in this work to develop this view in some 
detail as regards the phenomena with which psychology 
is concerned. 

My thanks are due to Professor John B. Watson anct 
to Dr. T. P. Nunn for reading my MSS. at an early stage 
and helping me with many valuable suggestions ; also 
to Mr. A. Wohlgemuth for much very useful information 
as regards important literature. I have also to acknow- 
ledge the help of the editor of this Library of Philosophy,, 
Professor Muirhead, for several suggestions by which I have 

The work has been given in the form of lectures both 
in London and Peking, and one lecture, that on Desire, 
has been published in the Athcnceum. 

There are a few allusions to China in this book, all 
of which were written before I had been in China, and 
are not intended to be taken by the reader as geographi- 
cally accurate. I have used "China" merely as a 
synonym for "a distant country/' when I wanted illus- 
trations of unfamiliar things. 


January 1921. 









VI. INTROSPECTION . . . . .108 



IX. MEMORY ...... 157 



XII. BELIEF . . . . . .231 



INDEX ....... 309 



THERE are certain occurrences which we are in the habit 
of calling " mental." Among these we may take as 
typical believing and desiring. The exact definition of 
the word " mental " will, I hope, emerge as the lectures 
proceed ; for the present, I shall mean by it whatever 
occurrences would commonly be called mental. 

I wish in these lectures to analyse as fully as I can 
what it is that really takes place when we, e.g. believe 
or desire. In this first lecture I shall be concerned to 
refute a theory which is widely held, and which I formerly 
held myself : the theory that the essence of everything 
mental is a certain quite peculiar something called " con- 
sciousness," conceived either as a relation to objects, or 
as a pervading quality of psychical phenomena. 

The reasons which I shall give against this theory will 
be mainly derived from previous authors. There ar^ 
two sorts of reasons, which will divide my lecture into 
two parts : \ 

(i) Direct reasons, derived frdm^ analysis and its 
difficulties ; 


(2) Indirect reasons, derived from observation of 
animals (comparative psychology) and of the 
insane and hysterical (psycho-analysis). 

Few things are more firmly established in popular 
philosophy than the distinction between mind and matter. 
Those who are not professional metaphysicians are willing 
to confess that they do not know what mind actually is, 
or how matter is constituted ; but they remain convinced 
that there is an impassable gulf between the two, and 
that both belong to what actually exists in the world. 
Philosophers, on the other hand, have maintained often 
that matter is a mere fiction imagined by mind, and 
sometimes that mind is a mere property of a certain 
kind of matter. Those who maintain that mind is the 
reality and matter an evil dream are called " idealists " 
a word which has a different meaning in philosophy 
from that which it bears m ordinary life. Those who 
argue that matter is the reality and mind a mere property 
of protoplasm are called " materialists." They have been 
rare among philosophers, but common, at certain periods,, 
among men of science. Idealists, materialists, and ordin- 
ary mortals have been in agreement on one point : that 
they knew sufficiently what they meant by the words 
" mind " and " matter " to be able to conduct their debate 
intelligently. Yet it was just in this point, as to which 
they were at one, that they seem to me to have been 
all alike in error. 

The stuff of which the world of our experience is com- 
posed is, in my belief, neither mind nor matter, but 
something more primitive than either. Both mind and 
matter seem to be composite, and the stuff of which they 
are compounded lies in a sense between the two, in a 


sense above them both, like a common ancestor. As 
regards matter, I have set forth my reasons for this view 
on former occasions, 1 and I shall not now repeat them. 
But the question of mind is more difficult, and it is this 
question that I propose to discuss in these lectures. A 
great deal of what I shall have to say is not original ; 
indeed, much recent work, in various fields, has tended 
to show the necessity of such theories as those which I 
shall be advocating. Accordingly in this first lecture I 
shall try to give a brief description of the systems of 
ideas within which our investigation is to be carried on. 
If there is one thing that may be said, in the popular 
estimation, to characterize mind, that one thing is " con- 
sciousness." We say that we are " conscious " of what 
we see and hear, of what we remember, and of our own 
thoughts and feelings. Most of us believe that tables 
and chairs are not " conscious." We think that when 
we sit in a chair, we are aware of sitting in it, but it is 
not aware of being sat in. It cannot for a moment be 
doubted that we are right in believing that there is some 
difference between us and the chair in this respect : so 
much may be taken as fact, and as a datum for our inquiry. 
But as soon as we try to say what exactly the difference 
is, we become involved in perplexities. Is " conscious- 
ness " ultimate and simple, something to be merely 
accepted and contemplated ? Or is it something complex, 
perhaps consisting in our way of behaving in the presence 
of objects, or, alternatively, in the existence in us of 
things called " ideas," having a certain relation to objects, 
though different from them, and only symbolically re- 
presentative of them ? Such questions are not easy to 

* Our Knowledge of the External World (Allen & Unwin), Chapters 
III and IV. Also Mysticism and Logic, Essays VII and VIII. 


answer ; but until they are answered we cannot profess 
to know what we mean by saying that we are possessed 
of " consciousness." 

Before considering modern theories, let us look first 
at consciousness from the standpoint of conventional 
psychology, since this embodies views which naturally 
occur when we begin to reflect upon the subject. For 
this purpose, let us as a preliminary consider different 
ways of being conscious. 

First, there is the way of perception. We " perceive " 
tables and chairs, horses and dogs, our friends, traffic 
passing in the street in short, anything which we recog- 
nize through the senses. I leave on one side for the 
present the question whether pure sensation is to be 
regarded as a form of consciousness : what I am speaking 
of now is perception, where, according to conventional 
psychology, we go beyond the sensation to the " thing " 
which it represents. When you hear a donkey bray, 
you not only hear a noise, but realize that it comes from 
a donkey. When you see a table, you not only see a 
coloured surface, but realize that it is hard. The addition 
of these elements that go beyond crude sensation is said 
to constitute perception. We shall haVe more to say 
about this at a later stage. For the moment, I am 
merely concerned to note that perception of objects is 
one of the most obvious examples of what is called " con- 
sciousness." We are " conscious " of anything that we 

We may take next the way of memory. If I set to 
work to recall what I did this morning, that is a form 
of consciousness different from perception, since it is 
concerned with the past. There are various problems 
as to how we can be conscious now of what no longer 


exists. These will be dealt with incidentally when we 
come to the analysis of memory. 

From memory it is an easy step to what are called 
" ideas " not in the Platonic sense, but in that of Locke, 
Berkeley and Hume, in which they are opposed to " im- 
pressions." You may be conscious of a friend either by 
seeing him or by " thinking " of him ; and by " thought " 
you can be conscious of objects which cannot be seen, 
such as the human race, or physiology, " Thought " 
in the narrower sense is that form of consciousness which 
consists in " ideas " as opposed to impressions or mere 

We may end our preliminary catalogue with belief, 
by which I mean that way of being conscious which may 
be either true or false. We say that a man is " conscious 
of looking a fool," by which we mean that he believes 
he looks a fool, and is not mistaken in this belief. This 
is a different form of consciousness from any of the earlier 
ones. It is the form which gives " knowledge " in the 
strict sense, and also error. It is, at least apparently, 
more complex than our previous forms of consciousness ; 
though we shall find that they are not so separable from 
it as they might appear to be. 

Besides ways of being conscious there are other things 
that would ordinarily be called " mental," such as desire 
and pleasure and pain. These raise problems of their 
own, which we shall reach in Lecture III. But the hardest 
problems are those that arise concerning ways of being 
"conscious." These ways, taken together, are called the 
" cognitive " ^elements in mind, and it is these that will 
occupy us most during the following lectures. 

There is one element which seems obviously in common 
among the different ways of being conscious, and that is* 


that they are all directed to objects. We are conscious 
" of " something. The consciousness, it seems, is one 
thing, and that of which we are conscious is another thing. 
Unless we are to acquiesce in the view that we can never 
be conscious of anything outside our own minds, we 
must say that the object of consciousness need not be 
mental, though the consciousness must be.. (I am speak- 
ing within the circle of conventional doctrines, not 
expressing my own beliefs.) This direction towards 
an object is commonly regarded as typical of every form 
of cognition, and sometimes of mental life altogether. 
We may distinguish two different tendencies in traditional 
psychology. There are those who take mental phenomena 
naively, just as they would physical phenomena. This 
school of psychologists tends not to emphasize the object. 
On the other hand, there are those whose primary interest 
is in the apparent fact that we have knowledge, that there 
is a world surrounding us of which we are aware. These 
men are interested in the mind because of its relation to 
the world, because knowledge, if it is a fact, is a very 
mysterious one. Their interest in psychology is naturally 
centred in the relation of consciousness to its object, a 
problem which, properly, belongs rather to theory of 
knowledge. We may take as one of the best and most 
typical representatives of this school the Austrian psycholo- 
gist Brentano, whose Psychology from the Empirical 
Standpoint* though published in 1874, is still influential, 
and was the starting-point of a great deal of interesting 
work. He says (p. 115) : 

" Every psychical phenomenon is characterized by 
what the scholastics of the Middle Ages called the inten- 

* P$ychologie vom .cmpirischen Standpunkte, vol. i, 1874. (The 
second volume was never published.) 


tional (also the mental) inexistence of an object, and what 
we, although with not quite unambiguous expressions, 
would call relation to a content, direction towards an 
object (which is not here to be understood as a reality), 
or immanent objectivity. Each contains something in 
itself as an object, though not each in the same way. 
In presentation something is presented, in judgment 
something is acknowledged or rejected, in love something 
is loved, in hatred hated, in desire desired, and so on. 

" This intentional inexistence is exclusively peculiar 
to psychical phenomena. No physical phenomenon 
shows anything similar. And so we can define psychical 
phenomena by saying that they are phenomena which 
intentionally contain an object in themselves." 

The view here expressed, that relation to an object is 
an ultimate irreducible characteristic of mental phenomena, 
is one which I shall be concerned to combat. Like Bren- 
tano, I am interested in psychology, not so much for its 
own sake, as for the light that it may throw on the 
problem of knowledge. Until very lately I believed, as he 
did, that mental phenomena have essential reference to 
objects, except possibly in the case of pleasure and pain. 
Now I no longer believe this, even in the case of know- 
ledge. I shall try to make my reasons for this rejection 
clear as we proceed. It must be evident at first glance 
that the analysis of knowledge is rendered more difficult 
by the rejection ; but the apparent simplicity of Brentano's 
view of knowledge will be found, if I am not mistaken, 
incapable of maintaining itself either against an analytic 
scrutiny or against a host of facts in psycho-analysis 
and animal psychology. I do not wish to minimize the 
problems. I will merely observe, in mitigation of our 
prospective labours, that thinking, however it is to be 


analysed, is in itself a delightful occupation, and that there 
is no enemy to thinking so deadly as a false simplicity. 
Travelling, whether in the mental or the physical world,. 
is a joy, and it is good to know that, in the mental 
world at least, there are vast countries still very imper- 
fectly explored. ? 

The view expressed by Brentano has been held very 
generally, and developed by many writers. Among 
these we may take as an example his Austrian successor 
Meinong. 1 According to him there are three elements 
involved in the thought of an object. These three he 
calls the act, the content and the , object. The act is the 
same in any two cases of the same kind of consciousness ; 
for instance, if I think of Smith or think of Brown, the 
act of thinking, in itself, is exactly similar on both occa- 
sions. But the content of my thought, the particular 
event that is happening in my mind, is different when I 
think of Smith and when I think of Brown. The content, 
Meinong argues, must not be confounded with the object, 
since the content must exist in my mind at the moment 
when I have the thought, whereas the object need not do 
so. The object may be something past or future ; it 
may be physical, not mental ; it may be something 
abstract, like equality for example ; it may be something 
imaginary, like a golden mountain ; or it may even be 
something self-contradictory, like a round square. But 
in all these cases, so he contends, the content exists when 
the thought exists, and is what distinguishes it, as an 
occurrence, from other thoughts. 

* See, e.g. his article : " Ueber Gegenstande hoherer Ordnung 
trad deren Verhaltnisa zur inneren Wahrnehmung/' Zeitschrift fur 
Psychologie und Physiologic der Sinnesorgane, vol. xxi, pp. 182-272 
(1899), especially pp. 185-8. 


To make this theory concrete, let us suppose that you 
are thinking of St. Paul's. Then, according to Meinong, 
we have to distinguish three elements which are necessarily 
combined in constituting the one thought. First, there 
is the act of thinking, which would be just the same 
whatever you were thinking about. Then there is what 
makes the character of the thought as contrasted with 
other thoughts ; this is the content. And finally there 
is St. Paul's, which is the object of your thought. There 
must be a difference between the content of a thought 
and what it is about, since the thought is here and now, 
whereas what it is about may not be ; hence it is clear 
that the thought is not identical with St. Paul's. This 
seems to show that we must distinguish between content 
and object. But if Meinong is right, there can be no 
thought without an object : the connection of the two is 
essential. The object might exist without the thought, 
but not the thought without the object : the three ele- 
ments of act, content and object are all required to con- 
stitute the one single occurrence called " thinking of St. 

The above analysis of a thought, though I believe it 
to be mistaken, is very useful as affording a schema 
in terms of which other theories can be stated. In the 
remainder of the present lecture I shall state in outline 
the view which I advocate, and show how various other 
views out of which mine has grown result from modifica- 
tions of the threefold analysis into act, content and 

The first criticism I have to make is that the act seems 
unnecessary and fictitious. The occurrence of the content 
of a thought constitutes the occurrence of the thought. 
Empirically, I cannot discover anything corresponding 


to the supposed act ; and theoretically I cannot see that 
it is indispensable. We say : " / think so-and-so," 
and this word " I " suggests that thinking is the act of a 
person. Meinong's " act " is the ghost of the subject, 
or what once was the full-blooded soul. It is supposed 
that thoughts cannot just come and go, but need a person 
to think them. Now, of course it is true that thoughts 
can be collected into bundles, so that one bundle is my 
thoughts, another is your thoughts, and a third is the 
thoughts of Mr. Jones. But I think the person is not 
an ingredient in the single thought : he is rather con- 
stituted by relations of the thoughts to each other and to 
the t>ody. This is a large question, which need not, in 
its entirety, concern us at present. All that I am con- 
cerned with for the moment is that the grammatical 
forms " I think," " you think/' and " Mr. Jones thinks," 
are misleading if regarded as indicating an analysis of 
a single thought. It would be better to say " it thinks 
in me," like " it rains here " ; or better still, " there is a 
thought in me." This is simply on the ground that what 
Meinong calls the act in thinking is not empirically dis- 
coverable, or logically deducible from what we can 

The next point of criticism concerns the relation of 
content and object. The reference of thoughts to objects 
is not, I believe, the simple direct essential thing that 
Brentano and Meinong represent it as being. It seems 
to me to be derivative, and to consist largely in beliefs : 
beliefs that what constitutes the thought is connected 
with various other elements which together make up the 
object. You have, say, an image of St. Paul's, or merely 
the word " St. Paul's " in your head. You believe, 
however vaguely and dimly, that this is connected with 


what you would see if you went to St. Paul's, or what 
you would feel if you touched its walls ; it is further 
connected with what other people see and feel, with services 
and the Dean and Chapter and Sir Christopher Wren. 
These things are not mere thoughts of yours, but your 
thought stands in a relation to them of which you are 
more or less aware. The awareness of this relation is 
a further thought, and constitutes your feeling that the 
original thought had an " object.' 1 But in pure imagina- 
tion you can get very similar thoughts without these 
accompanying beliefs ; and in this case your thoughts 
do not have objects or seem to have them. Thus in such 
instances you have content without object. On the 
other hand, in seeing or hearing it would be less misleading 
to say that you have object without content, since what 
you see or hear is actually part of the physical world, 
though not matter in the sense of physics. Thus the 
whole question of the relation of mental occurrences to 
objects grows very complicated, and cannot be settled 
by regarding reference to objects as of the essence of 
thoughts. All the above remarks are merely preliminary, 
and will be expanded later. 

Speaking in popular and unphilosophical terms, we 
may say that the content of a thought is supposed to be 
something in your head when you think the thought, 
while the object is usually something in the outer world. 
It is held that knowledge of the outer world is constituted 
by the relation to the object, while the fact that know- 
ledge is different from what it knows is due to the fact 
that knowledge comes by way of contents. We can begin 
to state the difference between realism and idealism 
in terms of this opposition of contents and objects. Speak- 
ing quite roughly and approximately, we may say that 


idealism tends to suppress the object, while realism tends 
to suppress the content. Idealism, accordingly, says 
that nothing can be known except thoughts, and all 
the reality that we know is mental ; while realism main- 
tains that we know objects directly, in sensation certainly, 
and perhaps also in memory and thought. Idealism does 
not say that nothing can be known beyond the present 
thought, but it maintains that the context of vague 
belief, which we spoke of in connection with the thought 
of St. Paul's, only takes you to other thoughts, never to 
anything radically different from thoughts. The difficulty 
of this view is in regard to sensation, where it seems as 
if* we came into direct contact with the outer world. But 
the Berkeleian way of meeting this difficulty is so familiar 
that I need not enlarge upon it now. I shall return to 
it in a later lecture, and will only observe, for the present, 
that there seem to me no valid grounds for regarding 
what we see and hear as not part of the physical world. 

Realists, on the other hand, as a rule, suppress the con- 
tent, and maintain that a thought consists either of act 
and object alone, or of object alone. I have been in the 
past a realist, and I remain a realist as regards sensation, 
but not as regards memory or thought. I will try to 
explain what seem to me to be the reasons for and 
against various kinds of realism. 

Modern idealism professes to be by no means confined 
to the present thought or the present thinker in regard 
to its knowledge ; indeed, it contends that the world is 
so organic, so dove-tailed, that from any one portion the 
whole can be inferred, as the complete skeleton of an 
extinct animal can be inferred from one bone. But the 
logic by which this supposed organic nature of the world 
is nominally demonstrated appears to realists, as it does 


to me, to be faulty. They argue that, if we cannot know 
the physical world directly, we cannot really know any- 
thing outside our own minds : the rest of the world may be 
merely our dream. This is a dreary view, and they there- 
fore seek ways of escaping from it. Accordingly they 
maintain that in knowledge we are in direct contact with 
objects, which may be, and usually are, outside our own 
minds. No doubt they are prompted to this view, in 
the first place, by bias, namely, by the desire to think 
that they can know of the existence of a world outside 
themselves. But we have to consider, not what led them 
to desire the view, but whether their arguments for it 
are valid. 

There are two different kinds of realism, according as 
we make a thought consist of act and object, or of object 
alone. Their difficulties are different, but neither seems 
tenable all through. Take, for the sake of definiteness, 
the remembering of a past event. The remembering 
occurs now, and is therefore necessarily not identical 
with the past event. So long as we retain the act, this 
need cause no difficulty. The act of remembering occurs 
now, and has on this view a certain essential relation to 
the past event which it remembers. There is no logical 
objection to this theory, but there is the objection, which 
we spoke of earlier, that the act seems mythical, and is 
not to be found by observation. If, on the other hand, 
we try to constitute memory without the act, we are driven 
to a content, since we must have something that happens 
now, as opposed to the event which happened in the past. 
Thus, when we reject the act, which I think we must, we 
are driven to a theory of memory which is more akin to 
idealism. These arguments, however, do not apply to 
sensation. It is especially sensation, I think, which is 


considered by those realists who retain only the object. 1 
Their views, which are chiefly held in America, are in 
large measure derived from William James, and before 
going further it will be well to consider the revolutionary 
doctrine which he advocated. I believe this doctrine 
contains important new truth, and what I shall have to 
say will be in a considerable measure inspired by it. 

William James's view was first set forth in an essay 
called " Does ' consciousness ' exist ? " a In this essay 
he explains how what used to be the soul has gradually 
been refined down to the " transcendental ego/' which, 
he says, " attenuates itself to a thoroughly ghostly condi- 
tion, being only a name for the fact that the ' content ' of 
experience is known. It loses personal form and activity 
these passing over to the content and becomes a bare 
Bewusstheit or Bewusstsein iiberhaupt, of which in 
its own right absolutely nothing can be said. I believe 
(he continues) that ' consciousness/ when once it 
has evaporated to this estate of pure diaphaneity, is 
on the point of disappearing altogether. It is the name 
of a nonentity, and has no right to a place among first 
principles. Those who still cling to it are clinging to a 
mere echo, the faint rumour left behind by the disap- 
pearing ' soul ' upon the air of philosophy " (p. 2). 

He explains that this is no sudden change in his 
opinions. " For twenty years past/' he says, " I have 
mistrusted ' consciousness ' as an entity ; for seven or 

1 This is explicitly the case with Mach's Analysis of Sensations, 
a book of fundamental importance in the present connection. 
(Translation of fifth German edition, Open Court Co., 1914. First 
German edition, 1886.) 

* Journal of Philosophy, Psychology and Scientific Methods, 
vol. i, 1904. Reprinted in Essays in Radical Empiricism (Long- 
mans, Green & Co., 1912), pp. 1-38, to which references in what 
follows refer. 


eight years past I have suggested its non-existence to my 
students, and tried to give them its pragmatic equivalent 
in realities of experience. It seems to me that the hour 
is ripe for it to be openly and universally discarded " (p. 3). 

His next concern is to explain away the air of paradox, 
for James was never wilfully paradoxical. " Undeniably," 
he says, " ' thoughts ' do exist." " I mean only to deny 
that the word stands for an entity, but to insist most 
emphatically that it does stand for a function. There is, 
I mean, no aboriginal stuff or quality of being, contrasted 
with that of which material objects are made, out of 
which our thoughts of them are made ; but there is a 
function in experience which thoughts perform, and for 
the performance of which this quality of being is invoked. 
That function is knowing " (pp. 3-4). 

James's view is that the raw material out of which 
the world is built up is not of two sorts, one matter and 
the other mind, but that it is arranged in different patterns 
by its inter-relations, and that some arrangements may 
be called mental, while others may be called physical. 

" My thesis is," he says, " that if we start with the 
supposition that there is only one primal stuff or material 
in the world, a stuff of which everything is composed, and 
if we call that stuff ' pure experience/ then knowing can 
easily be explained as a particular sort of relation towards 
one another into which portions of pure experience may 
enter. The relation itself is a part of pure experience ; 
one of its ' terms ' becomes the subject or bearer of the 
knowledge, the knower, the other becomes the object 
known " (p. 4). 

After mentioning the duality of subject and object, 
which is supposed to constitute consciousness, he 
proceeds in italics : " Experience, I believe, has no such 


inner duplicity ;, and the separation of it into consciousness 
and content comes, not by way of subtraction, but by way 
of addition " (p. 9). 

He illustrates his meaning by the analogy of paint 
as it appears in a paint-shop and as it appears in a 
picture : in the one case it is just " saleable matter," 
while in the otherit " performs a spiritual function. Just 
so, I maintain (he continues), does a given undivided 
portion of experience, taken in one context of associates, 
play the part of a knower, of a state of mind, of 
' consciousness ' ; while in a different context the 
same undivided bit of experience plays the part of a 
thing known, of an objective ' content/ In a word, 
iri one group it figures as a thought, in another group 
as a thing " (pp. 9-10). 

He does not believe in the supposed immediate cer- 
tainty of thought. " Let the case be what it may in 
others," he says, " I am as confident as I am of anything 
that, in myself, the stream of thinking (which I recog- 
nize emphatically as a phenomenon) is only a careless 
name for what, when scrutinized, reveals itself to con- 
sist chiefly of the stream of my breathing. The ' I 
think ' which Kant said must be able to accompany 
all my objects, is the ' I breathe ' which actually does 
accompany them " (pp. 36-37). 

The same view of " consciousness " is set forth in 
the succeeding esstfy, " A World of Pure Experience " 
(ib., pp. 39-91). The use of the phrase " pure experience " 
in both essays points to a lingering influence of idealism. 
" Experience," like " consciousness," must be a product, 
not part of the primary stuff of the world. It must 
be possible, if James is right in his main contentions, 
that roughly the same stuff, differently arranged, would 


not give rise to anything that could be called " experi- 
ence." This word has been dropped by the American 
realists, among whom we may mention specially 
Professor R. B. Pejpry of Harvard and Mr. Edwin B. 
Holt. The interests of this school are in general phil- 
oophy and the philosophy of the sciences, rather than in 
psychology ; they have derived a strong impulsion from 
James, but have more interest than he had in logic and 
mathematics and the abstract part of philosophy. They 
speak of " neutral " entities as the stuff out of which 
both mincT*~-f\d matter are constructed. Thus Holt 
says : "If the terms and propositions of logic must be 
substantialized, they are all strictly of one substance, 
for which perhaps the least dangerous name is neutral- 
stuff. The relation of neutral-stuff to matter and mind 
we shall have presently to consider at considerable 
length." ' 

My own belief for which the reasons will appear in 
subsequent lectures is that James is right in rejecting 
consciousness as an entity, and that the American realists 
are partly right, though not wholly, in considering that 
both mind and matter are composed of a neutral-stuff 
which, in isolation, is neither mental nor material. I 
should admit this view as regards sensations : what is 
heard or seen belongs equally to psychology and to 
physics. But I should say that images belong only to 
the mental world, while those occurrences (if any) which 
do not form part of any " experience " belong only to 
the physical world. There are, it seems to me, prima facie 
different kinds of causal laws, one belonging to physics 
and the other to psychology. The law of gravitation, for 
example, is a physical law, while the law of association 

1 The Concept of Consciousness (Geo. Allen & Co., 1914), p. 52. 


is a psychological law. Sensations are subject to both 
kinds of laws, and are therefore truly " neutral " in 
Holt's sense. But entities subject only to physical 
laws, or only to psychological laws, are not neutral, and 
may be called respectively purely material and purely 
mental. Even those, however, which are purely mental 
will not have that intrinsic reference to objects which 
Brentano assigns to them and which constitutes the 
essence of " consciousness " as ordinarily understood. 
But it is now time to pass on to other modern tendencies, 
also hostile to " consciousness." 

There is a psychological school called " Behaviourists," 
'of whom the protagonist is Professor John B. Watson, 1 
formerly of the Johns Hopkins University. To them also, 
on the whole, belongs Professor John Dewey, who, with 
James and Dr. Schiller, was one of the three founders 
of pragmatism. The view of the " behaviourists " is 
that nothing can be known except by external observa- 
tion. They deny altogether that there is a separate 
source of knowledge called " introspection," by which 
we can know things about ourselves which we could never 
observe in others. They do not by any means deny 
that all sorts of things may go on in our minds : they 
only say that such things, if they occur, are not sus- 
ceptible of scientific observation, and do not therefore 
concern psychology as a science. Psychology as a science, 
they say, is only concerned with behaviour, i.e. with 
what we do ; this alone, they contend, can be accurately 
observed. Whether we think meanwhile, they tell us, 
cannot be known ; in their observation of the behaviour 
of human beings, they have not so far found any evidence 

* See especially his Behavior : an Introduction to Comparative 
P$yckology t New York, 1914. 


of thought. True., we talk a great deal, and imagine 
that in so doing we are showing that we can think ; but 
behaviourists say that the talk they have to listen to 
can be explained without supposing that people think. 
Where you might expect a chapter on " thought pro- 
cesses " you come instead upon a chapter on " The 
.language Habit." It is humiliating to find how terribly 
adequate this hypothesis turns out to be. 

Behaviourism has not, however, sprung from observing 
the folly of men. It is the wisdom of animals that has 
suggested the view. It has always been a common topic 
of popular discussion whether animals " think/ 1 On 
this topic people are prepared to take sides without 
having the vaguest idea what they mean by " thinking." 
Those who desired to investigate such questions were 
led to observe the behaviour of animals, in the hope 
that their behaviour would throw some light on their 
mental faculties. At first sight, it might seem that 
this is so. People say that a dog "knows" its name 
because it comes when it is called, arid that it 
" remembers " its master, because it looks sad in his 
absence, but wags its tail and barks when he returns. 
That the dog behaves in this way is matter of observa- 
tion, but that it "knows" or "remembers" anything is 
an inference, and in fact a very doubtful one. The more 
such inferences are examined, the more precarious they 
are seen to be. Hence the study of animal behaviour 
has been gradually led to abandon all attempt at mental 
interpretation. And it can hardly be doubted that, in 
many cases of complicated behaviour very well adapted 
to its ends, there can be no prevision of those ends. The 
first time a bird builds a nest, we can hardly suppose 
it knows that there will be eggs to be laid in it, or that 


it will sit on the eggs, or that they will hatch into young 
birds. It does what it does at each stage because in- 
stinct gives it an impulse to do just that, not because 
it foresees and desires the result of its actions. 1 

Careful observers of animals, being anxious to avoid 
precarious inferences, have gradually discovered more 
and more how to give an account of the actions of 
animals without assuming what we call " consciousness. 1 ' 
It has seemed to the behaviourists that similar methods 
can be applied to human behaviour, without assuming 
anything not open to external observation. Let us 
give a crude illustration, too crude for the authors in 
question, but capable of affording a rough insight into 
their meaning. Suppose two children in a school, both 
of whom are asked " What is six times nine ? " One 
says fifty-four, the other says fifty-six. The one, we 
say, " knows " what six times nine is, the other does 
not. But all that we can observe is a certain 
language-habit. The one child has acquired the habit 
of saying " six times nine is fifty-four " ; the other 
has not. There is no more need of " thought " in 
this than there is when a horse turns into his accus- 
tomed stable ; there are merely more numerous and 
complicated habits. There is obviously an observable 
fact called " knowing " such-and-such a thing ; ex- 
aminations are experiments for discovering such facts. 
But all that is observed or discovered is a certain 
set of habits in the use of words. The thoughts (if any) 
in the mind of the examinee are of no interest to the 

1 An interesting discussion of the question whether instinctive 
actions, when first performed, involve any prevision, however 
vague, will be found in Lloyd Morgan's Instinct and Experience 
(Methuen, 1912), chap. ii. 


examiner ; nor has the examiner any reason to suppose 
even the most successful examinee capable of even the 
smallest amount of thought. 

Thus what is called " knowing," in the sense in which 
we can ascertain what other people " know," is a pheno- 
menon exemplified in their physical behaviour, including 
spoken and written words. There is no reason so 
Watson argues to suppose that their knowledge is 
anything beyond the habits shown in this behaviour : the 
inference that other people have something non-physical 
called " mind " or " thought " is therefore unwarranted. 

So far, there is nothing particularly repugnant to our 
prejudices in the conclusions of the behaviourists. We 
are all willing to admit that other people are thoughtless. 
But when it comes to ourselves, we feel convinced that 
we can actually perceive our own thinking. " Cogito, 
ergo sum " would be regarded by most people as having 
a true premiss. This, however, the behaviourist denies. 
He maintains that our knowledge of ourselves is no 
different in kind from our knowledge of other people. 
We may see more, because our own body is easier to 
observe than that of other people ; but we do not see 
anything radically unlike what we see of others. Intro- 
spection, as a separate source of knowledge, is entirely 
denied by psychologists of this school. I shall discuss 
this question at length in a later lecture ; for the present 
I will only observe that it is by no means simple, and 
that, though I believe the behaviourists somewhat over- 
state their case, yet there is an important element of 
truth in their contention, since the things which we 
can discover by introspection do not seem to differ in 
any very fundamental way from the things which we 
discover by external observation. 


So far, we have been principally concerned with know- 
ing. But it might well be maintained that desiring 
is what is really most characteristic of mind. Human 
beings are constantly engaged in achieving some end : 
they feel pleasure in success and pain in failure. In a 
purely material world, it may be said, there would be no 
opposition of pleasant and unpleasant, good and bad, 
what is desired and what is feared. A man's acts are 
governed by purposes. He decides, let us suppose, 
to go to a certain place, whereupon he proceeds to the 
station, takes his ticket and enters the train. If the 
usual route is blocked by an accident, he goes by some 
other route. All that he does is determined or so it 
seems by the end he has in view, by what lies in front 
of him, rather than by what lies behind. With dead 
matter, this is not the case. A stone at the top of a hill 
may start rolling, but it shows no pertinacity in trying 
to get to the bottom. Any ledge or obstacle will stop it, 
and it will exhibit no signs of discontent if this' happens. 
It is not attracted by the pleasantness of the valley, 
as a sheep or cow might be, but propelled by the steep- 
ness of the hill at the place where it is. In all this we 
have characteristic differences between the behaviour 
ol animals and the behaviour of matter as studied by 

Desire, like knowledge, is, of course, in one sense an 
observable phenomenon. An elephant will eat a bun, 
but not a mutton chop ; a duck will go into the water, 
but a hen will not. But when we think of our own 
desires, most people believe that we can know them 
by an immediate self-knowledge which does not depend 
upon observation of our actions. Yet if this were the 
case, it would be odd that people are so often mistaken 


as to what they desire. It is matter of common observa- 
tion that " so-and-so does not know his own motives," 
or that " A is envious of B and malicious about him, 
but quite unconscious of being so." Such people are 
called self-deceivers, and are supposed to have had to 
go through some more or less elaborate process of con- 
cealing from themselves what would otherwise have 
been obvious. I believe that this is an entire mistake. 
I believe that the discovery of our own motives can 
only be made by the same process by which we discover 
other people's, namely, the process of observing our 
actions and inferring the desire which could prompt 
them. A desire is " conscious " when we have told our- 
selves that we have it. A hungry man may say to 
himself : " Oh, I do want my lunch/ 1 Then his desire 
is " conscious." But it only differs from an " uncon- 
scious " desire by the presence of appropriate words, 
which is by no means a fundamental difference. 

The belief that a motive is normally conscious makes 
it easier to be mistaken as to our own motives than as 
to other people's. When some desire that we should 
be ashamed of is attributed to us, we notice that we 
have never had it consciously, in the sense of saying to 
ourselves, " I wish that would happen." We there- 
fore look for some other "interpretation of our actions, 
and regard our friends as very unjust when they refuse 
to be convinced by our repudiation of what wa hold to 
"be a calumny. Moral considerations greatly increase 
the difficulty of clear thinking in this matter. It is 
commonly argued that people are not to blame for un- 
conscious motives, but only for conscious ones. In order, 
therefore, to be wholly virtuous it is only necessary to 
repeat virtuous formulas. We say : " I desire to be kind 


to my friends, honourable in business, philanthropic 
towards the poor, public-spirited in politics." So long 
as we refuse to allow ourselves, even in the watches of 
the night, to avow any contrary desires, we may be 
bullies at home, shady in the City, skinflints in paying 
wages and profiteers in dealing with the public ; yet, 
if only conscious motives are to count in moral valuation, 
we shall remain model characters. This is an agreeable 
doctrine, and it is not surprising that men are un- 
willing to abandon it. But moral considerations are 
the worst enemies of the scientific spirit and we must 
dismiss them from our minds if we wish to arrive at 

I believe as I shall try to prove in a later lecture 
that desire, like force in mechanics, is of the nature 
of a convenient fiction for describing shortly certain laws 
of behaviour. A hungry animal is restless until it 
finds food ; then it becomes quiescent. The thing which 
will bring a restless condition to an end is' said to be 
what is desired. But only experience can show what 
will have this sedative effect, and it is easy to make 
mistakes. We feel dissatisfaction, and think that such- 
arid-such a thing would remove it ; but in thinking this, 
we are theorizing, not observing a patent fact. Our 
theorizing is often mistaken, and when it is mistaken 
there is a difference between what we think we desire 
and what in fact will bring satisfaction. This is such 
a common phenomenon that any theory of desire which 
fails to accout for it must be wrong. 

What have been called " unconscious " desires have 
been brought very much to the fore in recent years by 
psycho-analysis. Psycho-analysis, as every one knows, 
is primarily a method of understanding hysteria and 


certain forms of insanity * ; but it has been found that 
there is much in the lives of ordinary men and women 
which bears a humiliating resemblance to the delusions 
of the insane. The connection of dreams, .irrational 
beliefs and foolish actions with unconscious wishes has 
been brought to light, though with some exaggeration, 
by Freud and Jung and their followers. As regards 
the nature of these unconscious wishes, it seems to me 
.though as a layman I speak with diffidence that 
many psycho-analysts are unduly narrow ; no doubt the 
wishes they emphasize exist, but others, e.g. for honour 
and power, are equally operative and equally liable to 
concealment. This, however, does not affect the value of 
their general theories from the point of view of theoretic 
psychology, and it is from this point of view that their 
results are important for the analysis of mind. 

What, I think, is clearly established, is that a man's 
actions and beliefs may be wholly dominated by a desire 
of which he is quite unconscious, and which he indig- 
nantly repudiates when it is suggested to him. Such 
a desire is generally, in morbid cases, of a sort which 
the patient would consider wicked ; if he had to admit 

1 There is a wide field of " unconscious " phenomena which 
does not depend upon psycho-analytic theories. Such occurrences 
as automatic writing lead Dr. Morton Prince to say : " As I view 
this question of the subconscious, far too much weight is given 
to the point of awareness or not awareness of our conscious pro- 
cesses. * As a matter of fact, we find entirely identical phenomena, 
that is, identical in every respect but one that of awareness 
in which sometimes we are aware of these conscious phenomena 
and sometimes not " (p. 87 of Subconscious Phenomena, by various 
authors, Rebman). Dr. Morton Price conceives that there may be 
" consciousness " without " awareness." But this is a difficult 
view, and one which makes some definition of " consciousness " 
imperative. For my part, I cannot see how to separate conscious- 
ness from awareness. 



that he had the desire, he would loathe himself. Yet it 
is so strong that it must force an outlet for itself ; hence 
it becomes necessary to entertain whole systems of 
false beliefs in order to hide the nature of what is desired. 
The resulting delusions in very many cases disappear 
if the hysteric or lunatic can be made to face the facts 
about himself. The consequence of this is that the treat- 
ment of many forms of insanity has grown more psy- 
chological and less physiological than it ysed to be. 
Instead of looking for a physical defect in the brain, 
those who treat delusions look for the repressed desire 
which has found this contorted mode of expression. 
For those who do not wish to plunge into the somewhat 
repulsive and often rather wild theories of psycho-analytic 
pioneers, it will be worth while to read a little book 
by Dr. Bernard Hart on The Psychology of Insanity. 1 
On this question of the mental as opposed to the physio- 
logical study of the causes of insanity, Dr. Hart says : 

" The psychological conception [of insanity] is based 
on the view that mental processes can be directly studied 
without any reference to the accompanying changes 
which are presumed to take place in the brain, and that 
insanity may therefore be properly attacked from the 
standpoint of psychology " (p. 9). 

This illustrates a point which I am anxious to make 
clear from the outset. Any attempt to classify modern 
views, such as I propose to advocate, from the old stand- 
point of materialism and idealism, is only misleading. 
In certain respects, the views which \ shall be setting 
forth approximate to materialism ; in certain others, 
they approximate to its opposite. On this question of 

1 Cambridge, 1912 ; 2nd edition, 1914. The following references 
are to the second edition. 


the study of delusions, the practical effect of the modern 
theories, as Dr. Hart points out, is emancipation from 
the materialist method. On the other hand, as he also 
points out (pp. 38-9), imbecility and dementia still have 
to be considered physiologically, as caused by defects 
in the brain. There is no inconsistency in this. If, 
as we maintain, mind and matter are neither of them 
the actual stuff of reality, but different convenient 
groupings of an underlying material, then, clearly, 
the question whether, in regard to a given phenomenon, 
we are to seek a physical or a mental cause, is merely 
one to be decided by trial. Metaphysicians have argued 
endlessly as to the interaction of mind and matter. The 
followers of Descartes held that mind and matter are 
so different as to make any action of the one on the 
other impossible. When I will to move my arm, they 
said, it is not my will that operates on my arm, but 
God, who, by His omnipotence, moves my arm when- 
ever I want it moved. The modern doctrine of psycho- 
physical parallelism is not appreciably different from 
this theory of the Cartesian school. Psycho-physical 
parallelism is the theory that mental and physical events 
each have causes in their own sphere, but run on side 
by side owing to the fact that every state of the brain 
coexists with a definite state of the mind, and vice versa. 
This view of the reciprocal causal independence of mind 
and matter has no basis except in metaphysical theory. 1 
For us, there is no necessity to make any such assumption, 
which is very difficult to harmonize with obvious facts. 
I receive a letter inviting me to dinner : the letter is a 

1 It would seem, however, that Dr. Hart accepts this theory as 
a methodological precept. See his contribution to Subconscious 
Phenomena (quoted above), especially pp. 121-2. 


physical fact, but my apprehension of its meaning is 
mental. Here we have an effect of matter on mind. 
In consequence of my apprehension of the meaning of 
the letter, I go to the right place at the right time ; here 
we have an effect of mind on matter. I shall try to 
persuade you, in the course of these lectures, that matter 
is not so material and mind not so mental as is generally 
supposed. When we are speaking of matter, it will 
seem as if we were inclining to idealism ; when we are 
speaking of mind, it will seem as if we were inclining to 
materialism. Neither is the truth. Our world is to be 
constructed out of what the American realists call 
" neutral " entities, which have neither the hardness 
and indestructibility of matter, nor the reference to 
objects which is supposed to characterize mind. 

There is, it is true, one objection which might be felt, 
not indeed to the action of matter on mind, but to the 
action of mind on matter. The laws of physics, it may 
be urged, are apparently adequate to explain everything 
that happens to matter, even when it is matter in a 
man's brain. This, however, is only a hypothesis, not 
an established theory. There is no cogent empirical 
reason for supposing that the laws determining the 
motions of living bodies are exactly the same as those 
that apply to dead matter. Sometimes, of course, they 
are clearly the same. When a man falls from a precipice 
or slips on a piece of orange peel, his body behaves as if 
it were devoid of life. These are the occasions that make 
Bergson laugh. But when a man's bodily movements 
are what we call " voluntary," they are, at any rate 
prima facie, very different in their laws from the move- 
ments of what is devoid of life. I do not wish to say 
dogmatically that the difference is irreducible ; I think 


it highly probable that it is not. I say only that the 
study of the behaviour of living bodies, in the present 
state of our knowledge, is distinct from physics. The 
study of gases was originally quite distinct from that 
of rigid bodies, and would never have advanced to its 
present state if it had not been independently pursued. 
Nowadays both the gas and the rigid body are manu- 
factured out of a more primitive and universal kind of 
matter. In like manner, as a question of methodology, 
the laws of living bodies are to be studied, in the first 
place, without any undue haste to subordinate them 
to the laws of physics. Boyle's law and the rest had to 
be discovered before the kinetic theory of gases became 
possible. But in psychology we are hardly yet at the 
stage of Boyle's law. Meanwhile we need not be held up 
by the bogey of the universal rigid exactness of physics. 
This is, as yet, a mere hypothesis, to be tested empirically 
without any preconceptions. It may be true, or it may 
not. So far, that is all we can say. 

Returning from this digression to our main topic, 
namely, the criticism of " consciousness," we observe 
that Freud and his followers, though they have demon- 
strated beyond dispute the immense importance of 
" unconscious " desires in determining our actions and 
beliefs, have not attempted the task of telling us what 
an " unconscious " desire actually is, and have thus 
invested their doctrine with an air of mystery and mytho- 
logy which forms a large part of its popular attractive- 
ness. They speak always as though it were more normal 
for a desire to be conscious, and as though a positive 
cause had to be assigned for its being unconscious. 
Thus " the unconscious " becomes a sort of underground 
prisoner, living in a dungeon, breaking in at long intervals 


upon our daylight respectability with dark groans and 
maledictions and strange atavistic lusts. The ordinary 
reader, almost inevitably, thinks of this underground 
person as another consciousness, prevented by what 
Freud calls the " censor " from making his voice heard 
in company, except on rare and dreadful occasions when 
he shouts so loud that every one hears him and there is 
a scandal. Most of us like the idea that we could be 
desperately wicked if only we let ourselves go. For 
this reason, the Freudian " unconscious " has been a 
consolation to many quiet and well-behaved persons. 
I do not think the truth is quite so picturesque as 
this. m I believe an " unconscious " desire is merely a 
causal law of our behaviour, 1 namely, that we remain 
restlessly active until a certain state of affairs is realized, 
when we achieve temporary equilibrium If we know 
beforehand what this state of affairs is, our desire is 
conscious ; if not, unconscious. The unconscious desire 
is not something actually existing, but merely a 'tendency 
to a certain behaviour ; it has exactly the same status 
as a force in dynamics. The unconscious desire is in no 
way mysterious ; it is the natural primitive form of 
desire, from which the other has developed through our 
habit of observing and theorizing (often wrongly). 
It is not necessary to suppose, as Freud seems to do, 
that every unconscious wish was once conscious, and 
was then, in his terminology, " repressed " because we 
disapproved of it. On the contrary, we shall suppose 
that, although Freudian " repression " undoubtedly 
occurs and is important, it is not the usual reason for 
unconsciousness of our wishes. The usual reason is 
merely that wishes are all, to begin with, unconscious, 
i Cf. Hart, The Psychology of Insanity, p. 19. 


and only become known when they are actively noticed. 
Usually, from laziness, people do not notice, but accept 
the theory of human nature which they find current, 
and attribute to themselves whatever wishes this theory 
would lead them to expect. We used to be full of virtuous 
wishes, but since Freud our wishes have become, in the 
words of the Prophet Jeremiah, " deceitful above all 
things and desperately wicked." Both these views, 
in most of those who have held them, are the product 
of theory rather than observation, for observation requires 
effort, whereas repeating phrases does not. 

The interpretation of unconscious wishes which I 
have been advocating has been set forth briefly by 
Professor John B. Watson in an article called "The 
Psychology of Wish Fulfilment," which appeared in 
The Scientific Monthly in November, 1916. Two quota- 
tions will serve to show his point of view : 

" The Freudians (he says) have made more or less of 
a ' metaphysical entity ' out of the censor. They suppose 
that when wishes are repressed they are repressed into 
the ' unconscious/ and that this mysterious censor stands 
at the trapdoor lying between the conscious and the 
unconscious. Many of us do not believe in a world of 
the unconscious (a few of us even have grave doubts 
about the usefulness of the term consciousness), hence 
we try to explain censorship along ordinary biological 
lines. We believe that one group of habits can ' down ' 
another group of habits or instincts. In this case 
our ordinary system of habits those which we call 
expressive of our ' real selves ' inhibit or quench (keep 
inactive or partially inactive) those habits and instinc- 
tive tendencies which belong largely in the past " (p. 483). 

Again, after speaking of the frustration of some ira- 


pulses which is involved in acquiring the habits of a 
civilized adult, he continues : 

" It is among these frustrated impulses that I would 
find the biological basis of the unfulfilled wish. Such 
* wishes ' need never have been ' conscious/ and need 
never have been suppressed into Freud's realm of the un- 
conscious. It may be inferred from this that there is 
no particular reason for applying the term ' wish ' to 
such tendencies " (p. 485). 

One of the merits of the general analysis of mind which 
we shall be concerned with in the following lectures 
is that it removes the atmosphere of mystery from the 
phenomena brought to light by the psycho-analysts. 
Mystery is delightful, but unscientific, since it depends 
upon ignorance. Man has developed out of the animals, 
and there is no serious gap between him and the amoeba. 
Something closely analogous to knowledge and desire, 
as regards its effects on behaviour, exists among animals, 
even where what we call " consciousness " is- hard to 
believe in ; something equally analogous exists in our- 
selves in cases where no trace of " consciousness " can 
be found. It is therefore natural to suppose that, what- 
ever may be the correct definition of " consciousness," 
" consciousness " is not the essence of life or mind. In 
the ^ following lectures, accordingly, this term will dis- 
appear until we have dealt with words, when it will 
re-emerge as mainly a trivial and unimportant outcome 
of linguistic habits. 


IN attempting to understand the elements out of which 
mental phenomena are compounded, it is of the greatest 
importance to remember that from the protozoa to man 
there is nowhere a very wide gap either in structure or in 
behaviour. From this fact it is a highly probable inference 
that there is also nowhere a very wide mental gap. It 
is, of course, possible that there may be, at certain stages 
in evolution, elements which are entirely new from the 
standpoint of analysis, though in their nascent form they 
have little influence on behaviour and no very marked 
correlatives in structure. But the hypothesis of continuity 
in mental development is clearly preferable if no psycho- 
logical facts make it impossible. We shall find, if I am 
not mistaken, that there are no facts which refute the 
hypothesis of mental continuity, and that, on the other 
hand, this hypothesis affords a useful test of suggested 
theories as to the nature of mind. 

The hypothesis of mental continuity throughout 
organic evolution may be used in two different ways. On 
the one hand, it may be held that we have more know- 
ledge of our own minds than those of animals, and that 
we should use this knowledge to infer the existence of 
something similar to our own mental processes in animals 


and even in plants. On the other hand, it may be held 
that animals and plants present simpler phenomena^ 
more easily analysed than those of human minds ; on 
this ground it may be urged that explanations which 
are adequate in the case of animals ought not to be 
lightly rejected in the case of man. The practical effects 
of these two views are diametrically opposite : the first 
leads us to level up animal intelligence with what we 
believe ourselves to know about our own intelligence, 
while the second leads us to attempt a levelling down of 
our own intelligence to something not too remote from 
what we can observe in animals. It is therefore im- 
portant to consider the relative justification of the two 
ways of applying the principle of continuity. 

It is clear that the question turns upon another, namely, 
which can we know best, the psychology of animals or 
that of human beings ? If we can know most about 
animals, we shall use this knowledge as a basis for inference 
about human beings ; if we can know most about human 
beings, we shall adopt the opposite procedure. And the 
question whether we can know most about the psy- 
chology of human beings or about that of animals turns 
upon yet another, namely : Is introspection or external 
observation the surer method in psychology ? This is a 
question which I propose to discuss at length in Lec- 
ture VI ; I shall therefore content myself now with a 
statement of the conclusions to be arrived at. 

We know a great many things concerning ourselves 
which we cannot know nearly so directly concerning 
animals or even other people. We know when we have 
a toothache, what we are thinking of, what dreams we 
have when we are asleep, and a host of other occurrences 
which we only know about others when they tell us of 


them, or otherwise make them inferable by their be- 
haviour. Thus, so far as knowledge of detached facts 
is concerned, the advantage is on the side of self-knowledge 
as against external observation. 

But when we come to the analysis and scientific under- 
standing of the facts, the advantages on the side of self- 
knowledge become far less clear. We know, for example, 
that we have desires and beliefs, but we do not know 
what constitutes a desire or a belief. The phenomena 
are so familiar that it is difficult to realize how little we 
really know about them. We see in animals, and to 
a lesser extent in plants, behaviour more or less similar 
to that which, in us, is prompted by desires and beliefs, 
and we find that, as we descend in the scale of evolution, 
behaviour becomes simpler, more easily reducible to 
rule, more scientifically analysable and predictable. 
And just because we are not misled by familiarity we 
find it easier to be cautious in interpreting behaviour 
when we are dealing with phenomena remote from those 
of our own minds. Moreover, introspection, as psycho- 
analysis has demonstrated, is extraordinarily fallible 
even in cases where we feel a high degree of certainty. 
The net result seems to be that, though self-knowledge 
has a definite and important contribution to make to 
psychology, it is exceedingly misleading unless it is 
constantly checked and controlled by the test of external 
observation, and by the theories which such observation 
suggests when applied to animal behaviour. On the 
whole, therefore, there is probably more to be learnt 
about human psychology from animals than about animal 
psychology from human beings ; but this conclusion is 
one of degree, and must not be pressed beyond a point. 

It is only bodily phenomena that can be directly observed 


in animals, or even, strictly speaking, in other human 
beings. We can observe such things as their movements, 
their physiological processes, and the sounds they emit. 
Such things as desires and beliefs, which seem obvious 
to introspection, are not visible directly to external 
observation. Accordingly, if we begin our study of 
psychology by external observation, we must not begin 
by assuming such things as desires and beliefs, but only 
such things as external observation can reveal, which 
will be characteristics of the movements and physiological 
processes of animals. Some animals, for example, always 
run away from light and hide themselves in dark places. 
If you pick up a mossy stone which is lightly embedded 
in the earth, you will see a number of small animals 
scuttling away from the unwonted daylight and seeking 
again the darkness of which you have deprived them. 
Such animals are sensitive to light, in the sense that 
their movements are affected by it ; but it would be rash 
to infer that they have sensations in any way analogous 
to our sensations of sight. Such inferences, which go 
beyond the observable facts, are to be avoided with the 
utmost care. 

It is customary to divide human movements into three 
classes, voluntary, reflex and mechanical. We may 
illustrate the distinction by a quotation from William 
James (Psychology, i, 12) : 

" If I hear the conductor calling ' all aboard ' as I 
enter the depot, my heart first stops, then palpitates, 
and my legs respond to the air-waves falling on my 
tympanum by quickening their movements. If I stumble 
as I run, the sensation of falling provokes a movement 
of the hands towards the direction of the fall, the effect 
of which is to shield the body from too sudden a shock. 


If a cinder enter my eye, its lids close forcibly arjtd-jt 
copious flow of tears tends to wash it out;. 

" These three responses to a sensational stimulus 
differ, however, in many respects. The closure of the 
eye and the lachrymation are quite involuntary, and so is 
the disturbance of the heart. Such involuntary responses 
we know as ' reflex ' acts. The motion of the arms 
to break the shock of falling may also be called reflex, 
since it occurs too quickly to be deliberately intended. 
Whether it be instinctive or whether it result from the 
pedestrian education of childhood may be doubtful ; 
it is, at any rate, less automatic than the previous acts, 
for a man might by conscious effort learn to perform it 
more skilfully, or even to suppress it altogether. Actions 
of this kind, with which instinct and volition enter upon 
equal terms, have been called ' semi-reflex/ The act 
of running towards the train, on the other hand, has 
no instinctive element about it. It is purely the result 
of education, and is preceded by a consciousness of 
the purpose to be attained and a distinct mandate of 
the wjll. It is a ' voluntary act.' Thus the animal's 
reflex and voluntary performances shade into each other 
gradually, being connected by acts which may often 
occur automatically, but may also be modified by conscious 

" An outside observer, unable to perceive the accompany- 
ing consciousness, might be wholly at a loss to discriminate 
between the automatic acts and those which volition 
escorted. But if the criterion of mind's existence be 
the choice of the proper means for the attainment of a 
supposed end, all the acts alike seem to be inspired by 
intelligence, for appropriateness characterizes them all 
alike.' 1 


There is one movement, among those that James 
mentions at first, which is not subsequently classified, 
namely, the stumbling. This is the kind of movement 
which may be called " mechanical " ; it is evidently of 
a different kind from either reflex or voluntary move- 
ments, and more akin to the movements of dead matter, 
We may define a movement of an animal's body as 
" mechanical " when it proceeds as if only dead matter 
were involved. For example, if you fall over a cliff, 
you move under the influence of gravitation, and your 
centre of gravity describes just as correct a parabola as 
if you were already dead. Mechanical movements have 
not the characteristic of appropriateness, unless by acci- 
dent, as when a drunken man falls into a waterbutt and 
is sobered. But reflex and voluntary movements are not 
always appropriate, unless in some very recondite sense. 
A moth flying into a lamp is not acting sensibly ; no 
more is a man who is in such a hurry to get his ticket 
that he cannot remember the name of his destination. 
Appropriateness is a complicated and merely approxi- 
mate idea, and for the present we shall do well to 
dismiss it from our thoughts. 

As James states, there is no difference, from the point 
of view of the outside observer, between voluntary and 
reflex movements. The physiologist can discover that 
both depend upon the nervous system, and he may find 
that the movements which we call voluntary depend 
upon higher centres in the brain than those that are 
reflex. But he cannot discover anything as to the presence 
or absence of " will " or " consciousness," for these things 
can only be seen from within, if at all. For the present, 
we wish to place ourselves resolutely in the position 
of outside observers ; we will therefore ignore the dis- 


tinction between voluntary and reflex movements. We 
will call the two together " vital " movements. We may 
then distinguish " vital " from mechanical movements 
by the fact that vital movements depend for their causa- 
tion upon the special properties of the nervous system, < 
while mechanical movements depend only upon the 
properties which animal bodies share with matter in 

"There is need for some care if the distinction between 
mechanical and vital movements is to be made precise. 
It is quite likely that, if we knew more about animal 
bodies, we could deduce all their movements from the 
laws of chemistry and physics. It is already fairly easy 
to see how chemistry reduces to physics, i.e. how the 
differences between different chemical elements can be 
accounted for by differences of physical structure, the 
constituents of the structure being electrons which are 
exactly alike in all kinds of matter. We only know 
in part how to reduce physiology to chemistry, but we 
know enough to make it likely that the reduction is 
possibly. If we suppose it effected, what would become of 
the difference between vital and mechanical movements ? 
Some analogies will make the difference clear. A shock 
to a mass of dynamite produces quite different effects 
from an equal shock to a mass of steel : in the one case 
there is a vast explosion, while in the other case there 
is hardly any noticeable disturbance. Similarly, you 
may sometimes find on a mountain-side a large rock 
poised so delicately that a touch will set it crashing down 
into the valley, while the rocks all round are so firm 
that only a considerable force can dislodge them. What 
is analogous in these two cases is the existence of a great 
store of energy in unstable equilibrium ready to burst 


into violent motion by the addition of a very slight dis- 
turbance. Similarly, it requires only a very slight expen- 
diture of energy to send a post-card with the words " All 
is discovered ; fly 1 " but the effect in generating kinetic 
energy is said to be amazing. A human body, like^ a 
mass of dynamite, contains a stpe_of^nergyjn_unstable 
equilibrium, ready to be directed in this direction or 
that by a disturbance jvhich is ^physically very small, 
such as a spoken word 1 _ In all such cases the reduction 
of behaviour to physical laws can only be effected by 
entering into great minuteness ; so long as we confine 
ourselves to the observation of comparatively large 
masses, the way in which the equilibrium will be upset 
cannot be determined. Physicists distinguish between 
macroscopic and microscopic equations : the former 
determine the visible movements of bodies of ordinary 
size, the latter the minute occurrences in the smallest 
parts. It is only the microscopic equations that are 
supposed to be the same for all sorts of matter. The 
macroscopic equations result from a process of averaging 
out, and may be different in different c^ses. So, in 
our instance, the laws of macroscopic phenomena are 
different for mechanical and vital movements, though 
the laws of microscopic phenomena may be the same. 

We may say, speaking somewhat roughly, that a 
stimulus applied to the nervous system, like a spark to 
dynamite, is able to take advantage of the stored energy 
in unstable equilibrium, and thus to produce movements 
out of proportion to the proximate cause. Movements 
produced in this way are vital movements, while mechanical 
movements are those in which the stored energy of a 
living body is not involved. Similarly dynamite may be 
exploded, thereby displaying its characteristic properties, 


or may (with due precautions) be carted about like 
other mineral. The explosion is analogous to vital 
movements, the carting about to mechanical movements. 

Mechanical movements are of no interest to the psy- 
chologist, and it has only been necessary to define them 
in order to be able to exclude them. When a psychologist 
studies behaviour, it is only vital movements that concern 
him. We shall, therefore, proceed to ignore mechanical 
movements, and study only the properties of the 

The next point is to distinguish between movements 
that are instinctive and movements that are acquired 
by experience. This distinction also is to some extent 
one of degree. Professor Lloyd Morgan gives the following 
definition of " instinctive behaviour " : 

" That which is, on its first occurrence, independent 
of prior experience ; which tends to the well-being of the 
individual and the preservation of the race ; which is 
similarly performed by all members of the same more or 
less restricted group of animals ; and which may be 
subject o subsequent modification under the guidance of 
experience." x 

This definition is framed for the purposes of biology, 
and is in some respects unsuited to the needs of psychology. 
Though perhaps unavoidable, allusion to " the same more 
or less restricted group of animals " makes it impossible 
to judge what is instinctive in the behaviour of an 
isolated individual. Moreover, " the well-being of the 
individual and the preservation of the race " is only a 
usual characteristic, not a universal one, of the sort of 
movements that, from our point of view, are to be called 
instinctive ; instances of harmful instincts will be given 
* Instinct and Experience (Methuen, 1912^ p. 5 


shortly. The essential point of the definition, from our 
point of view, is that an instinctive movement is in- 
dependent of prior experience. 

We may say that an " instinctive " movement is a 
vital movement performed by an animal the first time 
that it finds itself in a novel situation ; or, more correctly, 
one which it would perform if the situation were novel. 1 
The~ tfistincts of an animal are different at different 
periods of its growth, and this fact may cause changes of 
behaviour which are not due to learning. The maturing 
and seasonal fluctuation of the sex-instinct affords a 
good illustration. When the sex-instinct first matures, 
the behaviour of an animal in the presence of a mate is 
different from its previous behaviour in similar circum- 
stances, but is not learnt, since it is just the same if the 
animal has never previously been in the presence of 
a mate. 

On the other hand, a movement is " learnt," or embodies 
a " habit," if it is due to previous experience of similar 
situations, and is not what it would be if the animal had 
had no such experience. 

There are various complications which blur the sharpness 
of this distinction in practice. To begin with, many 
instincts mature gradually, and while they are immature 
an animal may act in a fumbling manner which is very 
difficult to distinguish from learning. James (Psychology, 
ii, 407) maintains that children walk by instinct, and 
that the awkwardness of their first attempts is 'only 
due to the fact that the instinct has not yet ripened. 

He hopes that " some scientific widower, left alone with 


Though tliis can only be decided by comparison with other 
members of the species, and thus exposes us to the need of 
comparison which we thought an objection to Professor Lloyd 
Morgan's definition. 


his offspring at the critical moment, may ere long te^t 
this suggestion on the living subject." However this 
may be, he quotes evidence to show that " birds do not 
learn to fly," but fly by instinct when they reach the 
appropriate age (ib., p. 406). In the second place, instinct 
often gives only a rough outline of the sort of thing to 
do, in which case learning is necessary in order to acquire 
certainty and precision in action. In the third place, 
even in the clearest cases of acquired habit, such as 
speaking, some instinct is required to set in motion the 
process of learning. In the case of speaking, the chief 
instinct involved is commonly supposed to be that of 
imitation, but this may be questioned. (See Thorndike's 
Animal Intelligence, p. 253 ff.) 

In spite of these qualifications, the broad distinction 
between instinct and habit is undeniable. To take 
extreme cases, every animal at birth can take food by 
instinct, before it has had opportunity to learn ; on the 
other hand, no one can ride a bicycle by instinct, though, 
after learning, the necessary movements become just as 
automatic as if they were instinctive. 

The process of learning, which consists in the acquisition 
of habits, has been much studied in various animals. 1 
For example : you put a hungry animal, say a cat, in 
a cage which has a door that can be opened by lifting 
a latch ; outside the cage you put food. The cat at 
first dashes all round the cage, making frantic efforts to 
force a way out. At last, by accident, the latch is lifted, 
and the cat pounces on the food. Next day you repeat 
the experiment, and you find that the cat gets out much 
more quickly than the first time, although it still makes 

* The scientific study of this subject may almost be said to begin 
with Thorndike's Animal Intelligent* (Macmillan, 1911). 


some random movements. The third day it gets out 
still more quickly, and before long it goes straight to 
the latch and lifts it at once. Or you make a model 
of the Hampton Court maze, and put a rat in the middle, 
assaulted by the smell of food on the outside. The rat 
starts running down the passages, and is constantly 
stopped by blind alleys, but at last, by persistent attempts, 
it gets out. You repeat this experiment day after day ; 
you measure the time taken by the rat in reaching the 
food ; you find that the time rapidly diminishes, and 
that after a while the rat ceases to make any wrong 
turnings. It is by essentially similar processes that we 
learn speaking, writing, mathematics, or the government 
of an empire. 

Professor Watson (Behavior, pp. 262-3) h as an in- 
genious theory as to the way in which habit arises out 
of random movements. I think there is a reason why * 
his theory cannot be regarded as alone sufficient, but 
it seems not unlikely that it is partly correct. Supposie, 
for the sake of simplicity, that there are just ten random 
movements which may be made by the animal say, 
ten paths down which it may go and that only one of 
these leads to food, or whatever else represents success 
in the case in question. Then the successful movement 
always occurs during the animal's attempts, whereas 
each of the others, on the average, occurs in only half 
the attempts. Thus the tendency to repeat a previous 
performance (which is easily explicable without the inter- 
vention of " consciousness ") leads to a greater emphasis 
on the successful movement than on any other, and 
in time causes it alone to be performed. The objection 
to this view, if taken as the sole explanation, is that 
on improvement ought to set in till after the second trial, 


whereas experiment shows that already at the second 
attempt the animal does better than the first time. 
Something further is, therefore, required to account for 
the genesis of habit from random movements ; but I see 
no reason to suppose that what is further required involves 
" consciousness." 

Mr. Thorndike (op. cit. f p. 244) formulates two " pro 
visional laws of acquired behaviour or learning," as 
follows : 

" The Law of Effect is that : Of several responses made 
to the same situation, those which are accompanied or 
closely followed by satisfaction to the animal will, other 
things being equal, be more firmly connected with the 
situation, so that, when it recurs, they will be more likely 
to recur ; those which are accompanied or closely followed 
by discomfort to the animal will, other things being equal, 
have their connections with that situation weakened, so 
that, when it recurs, they will be less likely to occur. 
The greater the satisfaction or discomfort, the greater 
the strengthening or weakening of the bond. 

" Thp Law of Exercise is that : Any response to a 
situation will, other things being equal, be more strongly 
connected with the situation in proportion to the number 
of times it has been connected with that situation and 
to the average vigour and duration of the connections." 

With the explanation to be presently given of the mean- 
ing of " satisfaction " and " discomfort/' there seems 
every reason to accept these two laws. 

What is true of animals, as regards instinct and habit, 
is equally true of men. But the higher we rise in the 
evolutionary scale, broadly speaking, the greater becomes 
the power of learning, and the fewer are the occasions 
when pure instinct is exhibited unmodified in adult life. 


This applies with great force to man, so much so that 
some have thought instinct less important in the life 
of man than in that of animals. This, however, would 
be a mistake. Learning is only possible when instinct 
supplies the driving-force. The animals in cages, which 
gradually learn to get out, perform random movements 
at first, which are purely instinctive. But for these 
random movements, they would never acquire the experi- 
ence which afterwards enables them to produce the 
right movement. (This is partly questioned by Hobhouse * 
wrongly, I think.) Similarly, children learning to 
talk make all sorts of sounds, until one day the right 
sound comes by accident. It is clear that the original 
making of random sounds, without which speech would 
never be learnt, is instinctive. I think we may say the 
same of all the habits and aptitudes that we acquire : 
in all of them there has been present throughout some 
instinctive activity, prompting at first rather inefficient 
movements, but supplying the driving force while more 
and more effective methods are being acquired. A 
cat which is hungry smells fish, and goes to the larder. 
This is a thoroughly efficient method when there is fish 
in the larder, and it is often successfully practised by 
children. But in later life it is found that merely going 
to the larder does not cause fish to be there ; after a 
series of random movements it is found that this result 
is to be caused by going to the City in the morning and 
coming back in the evening. No one would have guessed 
a priori that this movement of a middle-aged man's 
body would cause fish to come out of the sea into 
his larder, but experience shows that it does, and the 
middle-aged man therefore continues to go to the City, 
Mind in Evolution (Macmillan, 1915)* PP- 236-237. 


just as the cat in the cage continues to lift the latch when 
it has once found it. Of course, in actual fact, human 
learning is rendered easier, though psychologically more 
complex, through language ; but at bottom language 
does not alter the essential character of learning, or 
of the part played by instinct in promoting learning. 
Language, however, is a subject upon which I do not 
wish to speak until a later lecture. 

The popular conception of instinct errs by imagining 
it to be infallible and preternaturally wise, as well as 
incapable of modification. This is a complete delusion. 
Instinct, as a rule, is very rough and ready, able to achieve 
its result under ordinary circumstances, but easily misled 
by anything unusual. Chicks follow their mother by 
instinct, but when they are quite young they will follow 
with equal readiness any moving object remotely re- 
sembling their mother, or even a human being (James, 
Psychology, ii, 396). Bergson, quoting Fabre, has made 
play with the supposed extraordinary accuracy of the 
solitary wasp Ammophila, which lays its eggs in a cater- 
pillar. , On this subject I will quote from Drever's 
Instinct in Man, p. 92 : 

" According to Fabre's observations, which Bergson 
accepts, the Ammophila stings its prey exactly and un- 
erringly in each of the nervous centres. The result is 
that the caterpillar is paralyzed, but not immediately 
killed, the advantage of this being that the larva cannot be 
injured by any movement of the caterpillar, upon which 
the egg is deposited, and is provided with fresh meat 
when the time comes. 

" Now Dr. and Mrs. Peckham have shown that the 
sting of the wasp is not unerring, as Fabre alleges, that 
the number of stings is not constant, that sometimes 


the caterpillar is not paralyzed, and sometimes it is killed 
outright, and that the different circumstances do not 
apparently make any difference to the larva, which is not 
injured by slight movements of the caterpillar, nor 
by consuming food decomposed rather than fresh 

This illustrates how love of the marvellous may mislead 
even so careful an observer as Fabre and so eminent 
a philosopher .as Bergson. 

In the same chapter of Dr. Drever's book there are 
some interesting examples of the mistakes made by 
instinct. I will quote one as a sample : 

" The larva of the Lomechusa beetle eats the young 
of the ants, in whose nest it is reared. Nevertheless, 
the ants tend the Lomechusa larvae with the same care 
they bestow on their own young. Not only so, but they 
apparently discover that the methods of feeding, which 
suit their own larvae, would prove fatal to the guests, 
and accordingly they change their whole system of 
nursing " (loc. cit., p. 106). 

Semon (Die Mneme, pp. 207-9) gives a good illustration 
of an instinct growing wiser through experience. He 
relates how hunters attract stags by imitating the sounds 
of other members of their species, male or female, but 
find that the older a stag becomes the more difficult it 
is to deceive him, and the more accurate the imitation 
has to be. 

The literature of instinct is vast, and illustrations 
might be multiplied indefinitely. The main points as 
regards instinct, which need to be emphasized as against 
the popular conceptions of it, are : 

(i) That instinct requires no prevision of the bio- 
logical end which it serves ; 


(2) That instinct is only adapted to achieve this 

end in the usual circumstances of the animal 
in question, and has no more precision than 
is necessary for success as a rule ; 

(3) That processes initiated by instinct often come 

to be performed better after experience ; 

(4) That instinct supplies the impulses to experi- 

mental movements which are required for the 
process of learning ; 

(5) That instincts in their nascent stages are easily 

modifiable, and capable of being attached to 
various sorts of objects. 

All the above characteristics of instinct can be established 
by purely external observation, except the fact that 
instinct does not require prevision. This, though not 
strictly capable of being proved by observation, is irre- 
sistibly suggested by the most obvious phenomena. 
Who can believe, for example, that a new-born baby is 
aware of the necessity of food for preserving life ? Or 
that insects, in laying eggs, are concerned for the preserva- 
tion of their species ? The essence of instinct, one might 
say, is that it provides a mechanism for acting without 
foresight in a manner which is usually advantageous 
biologically. It is partly for this reason that it is so 
important to understand the fundamental position of 
instinct in prompting both animal and human behaviour. 


DESIRE is a subject upon which, if I am not mistaken, 
true views can only be arrived at by an almost complete 
reversal of the ordinary unreflecting opinion. It is 
natural to regard desire as in its essence an attitude towards 
something which is imagined, not actual ; this something 
is called the end or object of the desire, and is said to 
be the purpose of any action resulting from the desire. 
We think of the content of the desire as being just like 
the content of a belief, while the attitude taken up towards 
the content is different. According to this theory, when 
we say : " I hope it will rain/' or " I expect it will 
rain," we express, in the first case, a desire, and in the 
second, a belief, with an identical content, namely, the 
image of rain. It would be easy to say that, just as 
belief is one kind of feeling in relation to this content, 
so desire is another kind. According to this view, what 
comes first in desire is something imagined, with a specific 
feeling related to it, namely, that specific feeling which we 
call " desiring "it. The discomfort associated with un- 
satisfied desire, and the actions which aim at satisfying 
desire, are, in this view, both of them effects of fhe desire. 
I think it is fair to say that this is a view against which 
common sense would not rebel ; nevertheless, I believe 


it to be radically mistaken. It cannot be refuted logically, 
but various facts can be adduced which make it gradually 
less simple and plausible, until at last it turns out to 
be easier to abandon it wholly and look at the matter 
in a totally different way. 

The first set of facts to be adduced against the common- 
sense view of desire are those studied by psycho-analysis. 
In all human beings, but most markedly in those suffering 
from hysteria and certain forms of insanity, we find 
what are called " unconscious " desires, which are 
commonly regarded as showing self-deception. Most 
psycho-analysts pay little attention to the analysis of 
desire, being interested in discovering by observation 
what it is that people desire, rather than in discovering 
what actually constitutes desire. I think the strangeness 
of what they report would be greatly diminished if it 
were expressed in the language of a behaviourist theory 
of desire, rather than in the language of every-day beliefs. 
The general description of the sort of phenomena that 
bear on our present question is as follows : A person 
states that his desires are so-and-so, and that it is these 
desires that inspire his actions ; but the outside observer 
perceives that his actions are such as to realize quite 
different ends from those which he avows, and that 
these different ends are such as he might be expected to 
desire. Generally they are less virtuous than his professed 
desires, and are therefore less agreeable to profess than 
these are. It is accordingly supposed that they really 
exist as desires for ends, but in a subconscious part of 
the mind, which the patient refuses to admit into conscious- 
ness for fear of having to think ill of himself. There 
are no doubt many cases to which such a supposition is 
applicable without obvious artificiality. But the deeper 


the Freudians delve into the underground regions of 
instinct, the further they travel from anything resembling 
conscious desire, and the less possible it becomes to 
believe that only positive self-deception conceals from, 
us that we really wish for things which are abhorrent 
to our explicit life. 

In the cases in question we have a conflict between 
the outside observer and the patient's consciousness. 
The whole tendency of psycho-analysis is to trust the 
outside observer rather than the testimony of introspection. 
I believe this tendency to be entirely right, but to demand 
a re-statement of what constitutes desire, exhibiting it as 
a causal law of our actions, not as something actually 
existing in our minds. 

But let us first get a clearer statement of the essential 
characteristic of the phenomena. 

A person, we find, states that he desires a certain end 
A, and that he is acting with a view to achieving it. We 
observe, however, that his actions are such as are likely 
to achieve a quite different end B, and that B is the 
sort of end that often seems to be aimed at by animals 
and savages, though civilized people are supposed 
have discarded it. We sometimes find also a whole 
set of false beliefs, of such a kind as to .persuade 
the patient that his actions are really a means to A, 
when in fact they are a means to B. For example, 
we have an impulse to inflict pain upon those whom 
we hate ; we therefore believe that they are wicked, 
and that punishment will reform them. This belief 
enables us to act upon the impulse to inflict pain, 
while believing that we are acting upon the desire to 
lead sinners to repentance. It is for this reason that 
the criminal law has been in all ages more severe than 


it would have been if the impulse to ameliorate the 
criminal had been what really inspired it. It seems 
simple to explain such a state of affairs as due to 
" self-deception," but this explanation is often mythical. 
Most people, in thinking about punishment, have had 
no more need to hide their vindictive impulses from 
themselves than they have had to hide the exponential 
theorem. Our impulses are not patent to a casual obser- 
vation, but are only to be discovered by a scientific study 
of our actions, in the course of which we must regard 
ourselves as objectively as we should the motions of 
the planets or the chemical reactions of a new element. 

The study of animals reinforces this conclusion, and is 
in many ways the best preparation for the analysis of 
desire. In animals we are not troubled by the disturbing 
influence of ethical considerations. In dealing with 
Human beings, we are perpetually distrac;ed by being 
told that such-and-such a view is^oomy or cynical or 
pessimistic : ages of human conceit have built up such a 
vast myth as to our wisdom and virtue that any intrusion 
of the mere scientific desire to know the facts is instantly 
resented by those who cling to comfortable illusions. 
But no one cares whether animals are virtuous or not, 
and no one is under the delusion that they are rational. 
Moreover, we do not expect them to be so " conscious," 
and are prepared to admit that their instincts prompt 
useful actions without any prevision of the ends which 
they achieve. For all these reasons, there is much in 
the analysis of mind which is more easily discovered by 
the study of animals than by the observation of human 

We all think that, by watching the behaviour of 
animals, we can discover more or less what they desire. 


If this is the case and I fully agree that it is desire 
must be capable of being exhibited in actions, for it is 
only the actions of animals that we can observe. They 
may have minds in which all sorts of things take place, 
but we can know nothing about their minds except by 
means of inferences from their actions ; and the more 
such inferences are examined, the more dubious they 
appear. It would seem, therefore, that actions alone 
must be the test of the desires of animals. From this it 
is an easy step to the conclusion that an animal's desire is 
nothing but a characteristic of a certain series of actions, 
namely, those which would be commonly regarded as 
inspired by the desire in question. And when it has 
been shown that this view affords a satisfactory account 
of animal desires, it is not difficult to see that the same 
explanation is applicable to the desires of human beings. 
We judge easily from the behaviour of an animal of a 
familiar kind whether it is hungry or thirsty, or pleased 
or displeased, or inquisitive or terrified. The verification 
of our judgment, so far as verification is possible, must 
be derived from the immediately succeeding actions of 
the animal. Most people would say that they infer first 
something about the animal's state of mind whether 
it is hungry or thirsty and so on and thence derive 
their expectations as to its subsequent conduct. But 
this detour through the animal's supposed mind is wholly 
unnecessary. We can say simply : The animal's be- 
haviour during the last minute has had those character- 
istics which distinguish what is called " hunger," and 
it is likely that its actions during the next minute will 
be similar in this respect, unless it finds food, or is inter- 
rupted by a stronger impulse, such as fear. An animal 
which is hungry is restless, it goes to the places where 


food is often to be found, it sniffs with its nose or peers 
with its eyes or otherwise increases the sensitiveness of 
its sense-organs ; as soon as it is near enough to food 
for its sense-organs to be affected, it goes to it with all 
speed and proceeds to eat ; after which, if the quantity 
of food has been sufficient, its whole demeanour changes : 
it may very likely lie down and go to sleep. These things 
and others like them are observable phenomena distinguish- 
ing a hungry animal from one which is not hungry. The 
characteristic mark by which we recognize a series of 
actions which display hunger is not the animal's menta] 
state, which we cannot observe, but something in its 
bodily behaviour ; it is this observable trait in the 
bodily behaviour that I am proposing to call " hunger," 
not some possibly mythical and certainly unknowable 
ingredient of the animal's mind. 

Generalizing what occurs in the case of hunger, we 
may say that what we call a desire in an animal is always 
displayed in a cycle of actions having certain fairly well- 
marked characteristics. There is first a state of activity, 
consisting, with qualifications to be mentioned presently, 
of movements likely to have a certain result ; these 
movements, unless interrupted, continue until the result 
is achieved, after which there is usually a period of 
comparative quiescence. A cycle of actions of this 
sort has marks by which it is broadly distinguished from 
the motions of dead matter. The most notable of these 
marks are (i) the appropriateness of the actions for the 
realization of a certain result ; (2) the continuance of 
action until tfrat result has been achieved. Neither of 
these can be pressed beyond a point. Either may be 
(a) to some extent present in dead matter, and (b) to 
a considerable extent absent in animals, while vegetables 


are intermediate, and display only a much fainter form 
of the behaviour which leads us to attribute desire to 
animals, (a) One might say rivers " desire " the sea : 
water, roughly speaking, remains in restless motion until 
it reaches either the sea or a place from which it cannot 
issue without going uphill, and therefore we might say 
that this is what it wishes while it is flowing. We do 
not say so, because we can account for the behaviour of 
water by the laws of physics ; and if we knew more about 
animals, we might equally cease to attribute desires to 
them, since we might find physical and chemical reactions 
sufficient to account for their behaviour, (b) Many 
of the movements of animals do not exhibit the charac- 
teristics of the cycles which seem to embody desire. 
There are first of all the movements which are " mechani- 
cal," such as slipping and falling, where ordinary physical 
forces operate upon the animal's body almost as if it 
were dead matter. An animal which falls over a cliff 
may make a number of desperate struggles while it is 
in the air, but its centre of gravity will move exactly as 
it would if the animal were dead. In this case, if the 
animal is killed at the end of the fall, we have, at first 
sight, just the characteristics of a cycle of actions em- 
bodying desire, namely, restless movement until the 
ground is reached, and then quiescence. Nevertheless, 
we feel no temptation to say that the animal desired 
what occurred, partly because of the obviously mechanical 
nature of the whole occurrence, partly because, when 
an animal survives a fall, it tends not to repeat the ex- 
perience. There may be other reasons also, but of them 
I do not wish to speak yet. Besides mechanical move- 
ments, there are interrupted movements, as when a 
bird, on its way to eat your best peas, is frightened away 


by the boy whom you are employing for that purpose. 
If interruptions are frequent and completion of cycles 
rare, the characteristics by which cycles are observed 
may become so blurred as to be almost unrecognizable. 
The result of these various considerations is that the 
differences between animals and dead matter, when 
we confine ourselves to external unscientific observation 
of integral behaviour, are a matter of degree and not 
very precise. It is for this reason that it has always been 
possible for fanciful people to maintain that even stocks 
and stones have some vague kind of soul. The evidence 
that animals have souls is so very shaky that, if it is 
assumed to be conclusive, one might just as well go a 
step further and extend the argument by analogy to 
all matter. Nevertheless, in spite of vagueness and 
doubtful cases, the existence of cycles in the behaviour 
of animals is a broad characteristic by which they are 
prima facie distinguished from ordinary matter ; and 
I think it is this characteristic which leads us to attribute 
desires to animals, since it makes their behaviour resemble 
what we do when (as we say) we are acting from desire. 

I shall adopt the following definitions for describing 
the behaviour of animals : 

A " behaviour-cycle " is a series of voluntary or reflex 
movements of an animal, tending to cause a certain 
result, and continuing until that result is caused, unless 
they are interrupted by death, accident, or some new 
behaviour-cycle. (Here " accident " may be defined as 
the intervention of purely physical laws causing mechanical 

The " purpose " of a behaviour-cycle is the result 
which brings it to an end, normally by a condition of 
temporary quiescence provided there is no interruption. 



An animal is said to " desire " the purpose of a behaviour- 
cycle while the behaviour-cycle is in progress. 

I believe these definitions to be adequate also to human 
purposes and desires, but for the present I am only occupied 
with animals and with what can be learnt by external 
observation. I am very anxious that no ideas should 
be attached to the words " purpose " and " desire " 
beyond those involved in the above definitions. 

We have not so far considered what is the nature of 
the initial stimulus to a behaviour-cycle. Yet it is here 
that the usual view of desire seems on the strongest 
ground. The hungry animal goes on making movements 
until it 'gets food ; it seems natural, therefore, to suppose 
that the idea of food is present throughout the process, 
and that the thought of the end to be achieved sets the 
whole process in motion. Such a view, however, is 
obviously untenable in many cases, especially where 
instinct is concerned. Take, for example, reproduction 
and the rearing of the young. Birds mate, build a nest, 
lay eggs in it, sit on the eggs, feed the young birds, and 
care for them until they are fully grown. It is totally 
impossible to suppose that this series of actions, which 
constitutes one behaviour-cycle, is inspired by any 
prevision of the end, at any rate the first time it is per- 
formed. 1 We must suppose that the stimulus to the 
performance of each act is an impulsion from behind, 
not an attraction from the future. The bird does what 
it does, '-at each stage, because it has an impulse to that 
particular action, not because it perceives that the whole 
cycle of actions will contribute to the preservation of 
the species. The same considerations apply to other 

1 For evidence as to birds' nests, cf. Semon, Die Mnemc, pp. 209, 



instincts. A hungry animal feels restless, and is Jed 
by instinctive impulses to perform the movements which 
give it nourishment ; but the act of seeking food is not 
sufficient evidence from which to conclude that the 
animal has the thought of food in its " mind." 

Coming now to human beings, and to what we know 
about our own actions, it seems clear that what, with 
us, sets a behaviour-cycle in motion is some sensation 
of the sort which we call disagreeable. Take the case 
of hunger : we have first an uncomfortable feeling inside, 
producing a disinclination to sit still, a sensitiveness to 
savoury smells, and an attraction towards any food that 
there may be in our neighbourhood. At any moment 
during this process we may become aware that we are 
hungry, in the sense of saying to ourselves, " I am hungry " ; 
but we may have been acting with reference to food for 
some time before this moment. While we are talking 
or reading, we m; *at in complete unconsciousness ; but 
we perform the actions of eating just as we should if we 
were conscious, and they cease when our hu ^r is appeased. 
What/we call " consciousness " seems to be a meic :-pctator 
of the process ; even when it issues orders, they are usi^lly, 
like those of a wise parent, just such as would have bee i 
obeyed even if they had not been given. This view 
may seem at first exaggerated, but the more our so-called 
volitions and their causes are examined, the more it is 
forced upon us. The part played by words in all this is 
complicated, and a potent source of confusions ; I shall 
return to it later. For the present, I am still concerned 
with primitive desire, as it exists in man, but in the form 
in which man shows his affinity to his animal ancestors. 

Conscious desire is made up partly of what is essential 
to desire, partly of beliefs as to what we want. It is 


important to be clear as to the part which does not consist 
of beliefs. 

The primitive non-cognitive element in desire seems 
to be a push, not a pull, an impulsion away from the 
actual, rather than an attraction towards the ideal. 
Certain sensations and other mental occurrences have 
a property which we call discomfort ; these cause such 
bodily movements as are likely to lead to their cessation. 
When the discomfort ceases, or even when it appreciably 
diminishes, we have sensations possessing a property 
which we call pleasure. Pleasurable sensations either 
stimulate no action at all, or at most stimulate such 
action as is likely to prolong them. I shall return shortly 
to the consideration of what discomfort and pleasure 
are in themselves ; for the present, it is their connection 
with action and desire that concerns us. Abandoning 
momentarily the standpoint of behaviourism, we may 
presume that hungry animal** experience sensations 
involving discomfort, and stimulating such movements 
as seem li^y to bring them to the food which 
is ou ' ;kie the cages. When they have reached the 
for a v and eaten it, their discomfort ceases and their 
^ensations become pleasurable. It seems, mistakenly, as 
if the animals had had this situation in mind throughout, 
when in fact they have been continually pushed by 
discomfort. And when an animal is reflective, like some 
men, it comes to think that it had the final situation in 
mind throughout ; sometimes it comes to know what 
situation will bring satisfaction, so that in fact the 
discomfort does bring the thought of what will allay it. 
Nevertheless the sensation involving discomfort remains 
the prime mover. 

This brings us to the question of the nature of dis- 
comfort and pleasure. Since Kant it has been customarv 


to recognize three great divisions of mental phenomena, 
which are typified by knowledge, desire and feeling, 
where " feeling " is used to mean pleasure and discomfort. 
Of course, " knowledge " is too definite a word : the 
states of mind concerned are grouped together as " cogni- 
tive," and are to embrace not only beliefs, but perceptions, 
doubts, and the understanding of concepts. " Desire," 
also, is narrower than what is intended : for example, 
will is to be included in this category, and in fact every- 
thing that involves any kind of striving, or " conation " 
as it is technically called. I do not myself believe that 
there is any value in this threefold division of the contents 
of mind. I believe that sensations (including images) 
supply all the " stuff " of the mind, and that everything 
else can be analysed into groups of sensations related 
in various ways, or characteristics of sensations or of 
groups of sensations. As regards belief, I shall give 
grounds for this view in later lectures. As regards desires, 
I have given some grounds in this lecture. For the 
present, it is pleasure and discomfort that concern us. 
There are broadly three theories that might be held 
in regard to them. We may regard them as separate 
existing items in those who experience them, or we may 
regard them as intrinsic qualities of sensations and other 
mental occurrences, or we may regard them as mere 
names for the causal characteristics of the occurrences 
which are uncomfortable or pleasant. The first of these 
theories, namely, that which regards discomfort and 
pleasure as actual contents in those who experience them, 
has, I think, nothing conclusive to be said in its favour. 1 

1 Various arguments in its favour are advanced by A. Wohlge- 
muth, " On the feelings and their neural correlate, with an examina- 
tion of tht nature of pain," British Journal of Psychology, viii, 4 


It is suggested chiefly by an ambiguity in the word 
" pain," which has misled many people, including 
Berkeley, whom it supplied with one of his arguments 
for subjective idealism. We may use " pain " as the 
opposite of " pleasure/' and " painful " as the opposite 
of " pleasant/' or we may use " pain "to mean a certain 
sort of sensation, on a l^vel with the sensations of heat 
and cold and touch. Tffce latter use of the word has 
prevailed in psychological literature, and it is now no 
longer used as the opposite of " pleasure." Dr. H. Head, 
in a recent publication, has stated this distinction as 
follows : x 

" It fe necessary at the outset to distinguish clearly 
between ' discomfort ' and ' pain/ Pain is a distinct 
sensory quality equivalent to heat and cold, and its 
intensity can be roughly graded according to the force 
expended in stimulation. Discomfort, on the other 
hand, is that feeling-tone which is directly opposed to 
pleasure. It may accompany sensations not in themselves 
essentially painful, as for instance that produced by 
tickling the sole of the foot. The reaction produced 
by repeated pricking contains both these elements ; for 
it evokes that sensory quality known as pain, accompanied 
by a disagreeable feeling-tone, which we have called 
discomfort. On the other hand, excessive pressure, 
except when applied directly over some nerve-trunk, 
tends to excite more discomfort than pain/' 

The confusion between discomfort and pain has made 

(1917). But as these arguments are largely a reductio ad absurdum 
of other theories, among which that which I am advocating is not 
included, I cannot regard them as establishing their contention. 

* " Sensation and the Cerebral Cortex/' Brain, vol. xli, part ii 
(September, 1918), p. 90. Cf. also Wohlgemuth, loc. cit. t pp. 437, 



people regard discomfort as a more substantial thing 
than it is, and this in turn has reacted upon the view 
taken of pleasure, since discomfort and pleasure are 
evidently on a level in this respect. As soon as discomfort 
is clearly distinguished from the sensation of pain, it 
becomes more natural to regard discomfort and pleasure 
as properties of mental occurrences than to regard them 
as separate mental occurrences on their own account. 
I shall therefore dismiss the view that they are separate 
mental occurrences, and regard them as properties of 
such experiences as would be called respectively un- 
comfortable and pleasant. 

It remains to be examined whether they are actual 
qualities of such occurrences, or arc merely differences 
as to causal properties. I do not myself see any way of 
deciding this question ; either view seems equally capable 
of accounting for the facts. If this is true, it is safer 
to avoid the assumption that there are such intrinsic 
qualities of mental occurrences as are in question, and 
to assume only the causal differences which are un- 
deniable. Without condemning the intrinsic theory, 
we ckn define discomfort and pleasure as consisting 
in causal properties, and say only what will hold on 
either of the two* theories. Following this course, we 
shall say : 

" Discomfort " is a property of a sensation or other 
mental occurrence, consisting in the fact that the occurrence 
in question stimulates voluntary or reflex movements 
tending to produce some more or less definite change 
involving the cessation of the occurrence. 

" Pleasure " is a property of a sensation or other mental 
occurrence, consisting in the fact that the occurrence 
in question either does not stimulate any voluntary or 


reflex movement, or, if it does, stimulates only such as 
tend to prolong the occurrence in question. 1 

" Conscious " desire, which we have now to consider, 
consists of desire in the sense hitherto discussed, together 
with a true belief as to its " purpose," i.e. as to the state 
of affairs that will bring quiescence with cessation of 
the discomfort. If our theory of desire is correct, a 
belief as to its purpose may very well be erroneous, since 
only experience' can show what causes a discomfort to 
cease. When the experience needed is common and 
simple, as in the case of hunger, a mistake is not very 
probable. But in other cases e.g erotic desire in those 
who have had little or no experience of its satisfaction 
mistakes are to be expected, and do in fact very often 
occur. The practice of inhibiting impulses, which is to 
a great extent necessary to civilized life, makes mistakes 
easier, by preventing experience of the actions to which 
a desire would otherwise lead, and by often causing the 
inhibited impulses themselves to be unnoticed or quickly 
forgotten. The perfectly natural mistakes which thus 
arise constitute a large proportion of what is, mistakenly 
in part, called self-deception, and attributed by Freud to 
the "censor." 

But there is a further point which needs emphasizing, 
namely, that a belief that something is desired has often 
a tendency to cause the very desire that is believed in. 
It is this fact that makes the effect of " consciousness " 
on desire so complicated, y^ 

When we believe that we desire a certain state of affairs, 

that often tends to cause a real desire for it. This is 

due partly to the influence of words upon our emotions, 

in rhetoric for example, and partly to the general fact 

Cf. Thorndike, of. cit., p. 245. 


that discomfort normally belongs to the belief that we 
desire such-and-such a thing that we do not possess. 
Thus what was originally a false opinion as to the object 
of a desire acquires a certain truth : the false opinion 
generates a secondary subsidiary desire, which neverthe- 
less becomes real. Let us take an illustration. Suppose 
you have been jilted in a way which wounds your vanity. 
Your natural impulsive desire will be of the sort expressed 
in Donne's poem : 

When by thy scorn, O Murderess, I am dead, 

in which he explains how he will haunt the poor lady 
as a ghost, and prevent her from enjoying a moment's 
peace. But two things stand in the way of your express- 
ing yourself so naturally : on the one hand, your vanity, 
which will not acknowledge how hard you are hit ; on 
the other hand, your conviction that you are a civilized 
and humane person, who could not possibly indulge so 
crude a desire as revenge. You will therefore experience 
a restlessness which will at first seem quite aimless, but 
will finally resolve itself in a conscious desire to change 
your profession, or go round the world, or conceal your 
identity and live in Putney, like Arnold Bennett's hero. 
Although the prime cause of this desire is a false judg- 
ment as to your previous unconscious desire, yet the new 
conscious desire has its own derivative genuineness, and 
may influence your actions to the extent of sending you 
round the world. The initial mistake, however, will have 
effects of two kinds. First, in uncontrolled moments, 
under the influence of sleepiness or drink or delirium, 
you will say things calculated to injure the faithless 
deceiver. Secondly, you will find travel disappointing, 
the East less fascinating than you had hoped unless, 


some day, you hear that the wicked one has in turn been 
jilted. If this happens, you will believe that you feel 
sincere sympathy, but you will suddenly be much more 
delighted than before with the beauties of tropical islands 
or the wonders of Chinese art. A secondary desire, 
derived from a false judgment as to a primary desire, 
has its own power of influencing action, and is therefore 
a real desire according to our definition. But it has not 
the same power as a primary desire of bringing thorough 
satisfaction when it is realized ; so long as the primary 
desire remains unsatisfied, restlessness continues in spite 
of the secondary desire's success. Hence arises a belief 
in the vanity of human wishes : the vain wishes are 
those that are secondary, but mistaken beliefs prevent 
us from realizing that they are secondary. 

What may, with some propriety, be called self-deception 
arises through the operation of desires for beliefs. We 
desire many things which it is not in our power to achieve : 
that we should be universally popular and admired, that 
our work should be the wonder of the age, and that the 
universe should be so ordered as to bring ultimate happiness 
to all, though not to our enemies until they have repented 
and been purified by suffering. Such desires are too 
large to be achieved through our own efforts. But it 
is found that a considerable portion of the satisfaction 
which these things would bring us if they were realized 
is to be achieved by the much easier operation of believing 
that they are or will be realized. This desire for beliefs, 
as opposed to desire for the actual facts, is a particular 
case of secondary desire, and, like all secondary desire, 
its satisfaction does not lead to a complete cessation ol 
the initial discomfort. Nevertheless, desire for beliefs, 
as opposed to desire for facts, is exceedingly potent both 


individually and socially. According to the form of 
belief desired, it is called vanity, optimism, or religion. 
-Those who have sufficient power usually imprison or 
put to death any one who tries to shake their faith in 
their own excellence or in that of the universe ; it is 
for this reason that seditious libel and blasphemy have 
always been, and still are, criminal offences. 

It is very largely through desires for beliefs that the 
primitive nature of desire has become so hidden, and 
that the part played by consciousness has been so confusing 
and so exaggerated. 

We may now summarize our analysis of desire and 

A mental occurrence of any kind sensation, image, 
belief, or emotion may be a cause of a series of actions, 
continuing, unless interrupted, until some more or less 
definite state of affairs is realized. Such a series of actions 
we call a " behaviour-cycle." The degree of definiteness 
may vary greatly : hunger requires only food in general, 
whereas the sight of a particular piece of food raises a 
desire which requires the eating of that piece of food. 
The property of causing such a cycle of occurrences is 
called " discomfort " ; the property of the mental occur- 
rences in which the cycle ends is called " pleasure." 
The actions constituting the cycle must not be purely 
mechanical, i.e. they must be bodily movements in whose 
causation the special properties oi nervous tissue are 
involved. The cycle ends in a condition of quiescence, or 
of such action as tends only to preserve the status quo. 
The state of affairs in which this condition of quiescence is 
achieved is called the " purpose " of the cycle, and the 
initial mental occurrence involving discomfort is called 
a " desire " for the state of affairs that brings quiescence. 


A desire is called " conscious " when it is accompanied 
by a true belief as to the state of affairs that will bring 
quiescence ; otherwise it is called " unconscious." All 
primitive desire is unconscious, and in human beings 
beliefs as to the purposes of desires are often mistaken. 
These mistaken beliefs generate secondary desires, which 
cause various interesting complications in the psychology 
of human desire, without fundamentally altering the 
character which it shares with animal desire. 



IN this lecture we shall be concerned with a very general 
characteristic which broadly, though not absolutely, dis- 
tinguishes the behaviour of living organisms from that 
of dead matter. The characteristic in question is this : 

The response of an organism to a given stimulus is very 
often dependent upon the past history of the organism, 
and not merely upon the stimulus and the hitherto dis- 
coverable present state of the organism. 

This characteristic is embodied in the saying " a burnt 
child fears the fire." The burn may have left no visible 
traces, yet it modifies the reaction of the child in the 
presence of fire. It is customary to assume that, in such 
cases, the past operates by modifying the structure of 
the brain, not directly. I have no wish to suggest that 
this hypothesis is false ; I wish only to point out that 
it is a hypothesis. At the end of the present lecture I 
shall examine the grounds in its favour. If we confine 
ourselves to facts which have been actually observed, 
we must say that past occurrences, in addition to the 
present stimulus and the present ascertainable con- 
dition of the organism, enter into the causation of the 



The characteristic is not wholly confined to living 
organisms. For example, magnetized steel looks just like 
steel which has not been magnetized, but its behaviour 
is in some ways different. In the case of dead matter, 
however, such phenomena are less frequent and im- 
portant than in the case of living organisms, and it is 
far less difficult to invent satisfactory hypotheses as to 
the microscopic changes of structure which mediate 
between the past occurrence and the present changed 
response. In the case of living organisms, practically 
everything that is distinctive both of their physical 
and of their mental behaviour is bound up with this 
persistent influence of the past. Further, speaking 
broadly, the change in response is usually of a kind that 
is biologically advantageous to the organism 

Following a suggestion derived from Semon (Die Mneme, 
Leipzig, 1904; 2nd edition, 1908, English translation, 
Allen & Unwin, 1921 ; Die mnemischen Empfindungen, 
Leipzig, 1909), we will give the name of " mnemic 
phenomena " to those responses of an organism which, 
so far as hitherto observed facts are concerned, can only 
be brought under causal laws by including past occurrences 
in the history of the organism as part of the causes of 
the present response. I do not mean merely what would 
always be the case that past occurrences are part of a 
chain of causes leading to the present event. I mean 
that, in attempting to state the proximate cause of the 
present event, some past event or events must be included, 
unless we take refuge in hypothetical modifications of 
brain structure. For example : you smell peat-smoke, 
and you recall some occasion when you smelt it before. 
The cause of your recollection, so far as hitherto observ- 
able phenomena are concerned, consists both of the peat- 
smoke (present stimulus) and of the former occasion (past 


experience). The same stimulus will not produce the 
same recollection in another man who did not share your 
former experience, although the former experience left 
no observable traces in the structure of the brain. Ac- 
cording to the maxim " same cause, same effect/' we 
cannot therefore regard the peat-smoke alone as the 
cause of your recollection, since it does not have the same 
effect in other cases. The cause of your recollection 
must be both the peat-smoke and the past occurrence. 
Accordingly your recollection is an instance of what we 
are calling " mnemic phenomena." 

Before going further, it will be well to give illustrations 
of different classes of mnemic phenomena. 

(a) Acquired Habits., In Lecture II we saw how animals 
can learn by experience how to get out of cages or mazes,, 
or perform other actions which are useful to them but 
not provided for by their instincts alone. A cat which 
is put into a cage of which it has had experience behaves 
differently from the way in which it behaved at first. 
We can easily invent hypotheses, which are quite likely 
to be true, as to connections in the brain caused by past 
experience, and themselves causing the different response. 
But the observable fact is that the stimulus of being in 
the cage produces differing results with repetition, and 
that the ascertainable cause of the cat's behaviour is 
not merely the cage and its own ascertainable organization, 
but also its past history in regard to the cage. From 
our present point of view, the matter is independent of 
the question whether the cat's behaviour is due to some 
mental fact called " knowledge," or displays a merely 
bodily habit. Our habitual knowledge is not always in 
our minds, but is called up by the appropriate stimuli. 
If we are asked " What is the capital of France ? " we 


answer " Paris," because of past experience ; the past 
experience is as essential as the present question in the 
causation of our response. Thus all our habitual know- 
ledge consists of acquired habits, and comes under the 
head of mnemic phenomena. 

(b) Images. I shall have much to say about images 
in a later lecture ; for the present I am merely concerned 
with them in so far as they are " copies " of past sensa- 
tions. When you hear New York spoken of, some image 
probably comes into your mind, either of the place 
itself (if you have been there), or of some picture of 
it (if you have not). The image is due to your past 
experience, as well as to the present stimulus of the 
words " New York." Similarly, the images you have 
in dreams are all dependent upon your past experience, 
as well as upon the present stimulus to dreaming. It is 
generally believed that all images, in their simpler parts, 
are copies of sensations ; if so, their mnemic character 
is evident. This is important, not only on its own account, 
but also because, as we shall see later, images play an 
essential part in what, is called " thinking." 

(c) Association. The broad fact of association, on the 
mental side, is that when we experience something which 
we have experienced before, it tends to call up the context 
of the former experience. The smell of peat-smoke 
recalling a former scene is an instance which we dis- 
cussed a moment ago. This is obviously a mnemic pheno- 
menon. There is also a more purely physical association, 
which is indistinguishable from physical habit. This is 
the kind studied by Mr. Thorndike in animals, where a 
certain simulus is associated with a certain act. This 
is the sort which is taught to soldiers in drilling, for 
example. In such a case there need not be anything 


mental, but merely a habit of the body. There is no 
essential distinction between association and habit, and 
the observations which we made concerning habit as 
a mnemic phenomenon are equally applicable to asso- 

(d) Non-sensational Elements in Perception. When we 
perceive any object of a familiar kind, much of what 
appears subjectively to be immediately given is really 
derived from past experience. When we see an object, 
say a penny, we seem to be aware of its " real " shape : 
we have the impression of something circular, not of 
something elliptical. In learning to draw, it is necessary 
to acquire the art of representing things according to 
the sensation, not according to the perception. And the 
visual appearance is filled out with feeling of what the 
object would be like to touch, and so on. This filling out 
and supplying of the " real " shape and so on consists 
of the most usual correlates of the sensational core in 
our perception. It may happen that, in the particular 
case, the real correlates are unusual ; for example, if 
what we are seeing is a carpet made to look like tiles. 
If so, the non-sensational part of our perception will be 
illusory, i.e. it will supply qualities which the object in 
question does not in fact have. But as a rule objects 
do have the qualities added by perception, which is to 
be expected, since experience of what is usual is the 
cause of the addition. If our experience had been different, 
we should not fill out sensation in the same way, except 
in so far as the filling out is instinctive, not acquired. 
It would seem that, in man, all that makes up space- 
perception, including the correlation of sight and touch 
and so on, is almost entirely acquired. In that case 
there is a large mnemic element in all the common per- 



ceptions by means of which we handle common objects. 
And, to take another kind of instance, imagine what our 
astonishment would be if we were to hear a cat bark or a 
dog mew. This emotion would be dependent upon past 
experience, and would therefore be a mnemic phenomenon 
according to the definition. 

(e) Memory as Knowledge. The kind of memory of 
which I am now speaking is definite knowledge of some 
past event in one's own experience. From time to time 
we remember things that haye happened to us, because 
something in the present reminds us of them. Exactly 
the same present fact would not call up the same memory 
if our -past experience had been different. Thus our 
remembering is caused by 

(1) The present stimulus, 

(2) The past occurrence. 

It is therefore a mnemic phenomenon accord ng to our 
definition. A definition of " mnemic phenomena " which 
did not include memory would, of course, be a bad one. 
The point of the definition is not that it includes memory, 
but that it includes it as one of a class of phenomena 
which embrace all that is characteristic in the subject- 
matter of psycho!ogy. 

(/) Experience. The word " experience " is often used 
very vaguely. James, as we saw, uses it to cover the whole 
primal stuff of the world, but this usage seems objection- 
able, since, in a purely physical world, things would happen 
^vithout there being any experience. It is only mnemic 
phenomena that embody experience. We may say that 
an animal " experiences " an occurrence when this 
occurrence modifies the animal's subsequent behaviour, 
i.e. when it is the mnemic portion of the cause of 


future occurrences in the animal's life. The burnt child 
that fears the fire has " experienced " the fire, whereas 
a stick that has been thrown on and taken off again 
has not " experienced " anything, since it offers no more 
resistance than before to being thrown on. The essence 
of " experience " is the modification of behaviour pro- 
duced by what is experienced. We might, in fact, 
define one chain of experience, or one biography, as a 
series of occurrences linked by mnemic causation. I 
think it is this characteristic, more than any other, 
that distinguishes sciences dealing with living organisms 
from physics. 

The best writer on mnemic phenomena known to me 
is Richard Semon, the fundamental part of whose theory 
I shall endeavour to summarize before going further : 

When an organism, either animal or plant, is subjected 
to a stimulus, producing in it some state of excitement, 
the removal of the stimulus allows it to return 
to a condition of equilibrium. But the new state of 
equilibrium is different from the old, as may be seen 
by thp changed capacity for reaction. The state of 
equilibrium before the stimulus may be called the " primary 
indifference-state " ; that after the cessation of the stimu- 
lus, the " secondary indifference-state." We define the 
" engraphic effect " of a stimulus as the effect in making 
a difference between the primary and secondary indiffer- 
ence-states, and this difference itself we define as the 
" engram " due to the stimulus. " Mnemic phenomena " 
are defined as those due to engrams ; in animals, they 
are specially associated with the nervous system, but 
not exclusively, even in man. 

When two stimili occur together, one of them, occur- 
ring afterwards, may call out the reaction for the other 


also. We call this an " ekphoric influence," and stimuli 
having this character are called " ekphoric stimuli." 
In such a case we call the engrams of the two stimuli 
" associated." All simultaneously generated engrams 
are associated ; there is also association of successively 
aroused engrams, though this is reducible to simultaneous 
association. In fact, it is not an isolated stimulus that 
leaves an engram, but the totality of the stimuli at any 
moment ; consequently any portion of this totality tends, 
if it recurs, to arouse the whole reaction which was aroused 
before. Semon holds that engrams can be inherited, 
and that an animal's innate habits may be due to the 
experience of its ancestors ; on this subject he refers to 
Samuel Butler. 

Semon formulates two " mnemic principles." The first, 
or " Law of Engraphy," is as follows : " All simultaneous 
excitements in an organism form a connected simultaneous 
excitement-complex, which as such worjcs engraphically, 
i.e. leaves behind a connected engram-complex, which in 
so far forms a whole " (Die mnemischen Empfindungen, 
p. 146). The second mnemic principle, or "Law of 
Ekphory," is as follows : " The partial return of the 
energetic situation which formerly worked engraphically 
operates ekphorically on a simultaneous engram-com- 
plex " (ib., p. 173). These two laws together represent 
in part a hypothesis (the engram), and in part an 
observable fact. The observable fact is that, when a 
certain complex of stimuli has originally caused a certain 
complex of reactions, the recurrence of part of the 
stimuli tends to cause the recurrence of the whole of 
the reactions. 

Semon's applications of his fundamental ideas in various 
directions are interesting and ingenious. Some of them 


will concern us later, but for the present it is the funda- 
mental character of mnemic phenomena that is in question. 

Concerning the nature of an engram, Semon confesses 
that at present it is impossible to say more than that it 
must consist in some material alteration in the body of 
the organism (Die mnemischen Empfindungen, p. 376). It 
is, in fact, hypothetical, invoked for theoretical uses, and 
not an outcome of direct observation. No doubt physio- 
logy, especially the disturbances of memory through 
lesions in the brain, affords grounds for this hypo- 
thesis ; nevertheless it does remain a hypothesis, the 
validity of which will be discussed at the end of this 

I am inclined to think that, in the present state of 
physiology, the introduction of the engram does not 
serve to simplify the account of mnemic phenomena 
We can, I think, formulate the known laws of such pheno- 
mena in terms, wholly, of observable facts, by recognizing 
provisionally what we may call " mnemic causation." 
By this I mean that kind of causation of which I spoke 
at the beginning of this lecture, that kind, namely, in 
which the proximate cause consists not merely of a pre- 
sent event, but of this together with a past event. I 
do not wish to urge that this form of causation is ulti- 
mate, but that, in the present state of our knowledge, it 
affords a simplification, and enables us to state laws of 
behaviour in less hypothetical terms than we should 
otherwise have to employ. 

The clearest instance of what I mean is recollection 
of a past eVent. What we observe is that certain present 
stimuli lead us to recollect certain occurrences, but that at 
times when we are not recollecting them, there is nothing 
discoverable in our minds that could be called memory 


of them. Memories, as mental facts, arise from time to 
time, but do not, so far as we can see, exist in any shape 
while they are " latent." In fact, when we say that they 
are " latent," we mean merely that they will exist under 
certain circumstances. If, then, there is to be some 
standing difference between the person who can remember 
a certain fact and the person who cannot, that standing 
difference must be, not in anything mental, but in the 
brain. It is quite probable that there is such a difference 
in the brain, but its nature is unknown and it remains 
hypothetical. Everything that has, so far, been made 
matter of observation as regards this question can be 
put together in the statement : When a certain complex 
of sensations has occurred to a man, the recurrence of 
part of the complex tends to arouse the recollection of 
the whole. In like manner, we can collect all mnemic 
phenomena in living organisms under a single law, which 
contains what is hitherto verifiable in Semon's two laws. 
This single law is : 

// a complex stimulus A has caused a complex reaction B 
in an organism, the occurrence of a part of A on a future 
occasion tends to cause the whole reaction B. 

This law would need to be supplemented by some 
account df the influence of frequency, and so on ; but 
it seems to contain the essential characteristic of mnemic 
phenomena, without admixture of anything hypothetical. 

Whenever the effect resulting from a stimulus to an 
organism differs according to the past history of the 
organism, without our being able actually to detect any 
relevant difference in its present structure, we will speak 
of " mnemic causation," provided we can discover laws 
embodying the influence of the past. In ordinary physical 
causation, as it appears to common sense, we have approxi- 


mate uniformities of sequence, such as " lightning is 
followed by thunder," " drunkenness is followed by head- 
ache," and so on. None of these sequences are theoreti- 
cally invariable, since something may intervene to dis- 
turb them. In order to obtain invariable physical laws, 
we have to proceed to differential equations, showing the 
direction of change at each moment, not the integral 
change after a finite interval, however short. But for 
the purposes of daily life many sequences are to all in- 
tents and purposes invariable. With the behaviour of 
human beings, however, this is by no means the case. 
If you say to an Englishman, " You have a smut on your 
nose," he will proceed to remove it, but there will be no 
such effect if you say the same thing to a Frenchman 
who knows no English. The effect of words upon the 
hearer is a mnemic phenomena, since it depends upon 
the past experience which gave him understanding of 
the words. If there are to be purely psychological causal 
laws, taking no account of the brain and the rest of the 
body, they will have to be of the form, not " X now causes 
Y now," but 

" A, B, C, . . . in the past, together with X now, 
cause Y now." For it cannot be successfully maintained 
that our understanding of a word, for example, is an 
actual existent content of the mind at times when we 
are not thinking of the word. It is merely what may be 
called a " disposition," i.e. it is capable of being aroused 
whenever we hear the word or happen to think of it. 
A " disposition " is not something actual, but merely 
the mnemic portion of a mnemic causal law. 

In such a law as " A, B, C, , . . in the past, together 
with X now, cause Y now," we will call A, B, C, . . . the 
mnemic cause, X the occasion or stimulus, and Y the 


reaction. All cases in which experience influences be- 
haviour are instances of mnemic causation. 

Believers in psycho-physical parallelism hold that psy- 
chology can theoretically be freed entirely from all de- 
pendence on physiology or physics. That is to say, they 
believe that every psychical event has a psychical cause 
and a physical concomitant. If there is to be parallelism, 
it is easy to prove by mathematical logic that the causa- 
tion in physical and psychical matters must be of the 
same sort, and it is impossible that mnemic causation 
should exist in psychology but not in physics. But if 
psychology is to be independent of physiology, and if 
physiology can be reduced to physics, it would seem that 
mnemic causation is essential in psychology. Otherwise 
we shall be compelled to believe that all our knowledge, 
all our store of images and memories, all our mental 
habits, are at all times existing in some latent mental 
form, and are not merely aroused by the stimuli which 
lead to their display. This is a very difficult hypothesis. 
It seems to me that if, as a matter of method rather 
than metaphysics, we desire to obtain as much indepen- 
dence for psychology as is practically feasible, we shall 
do better to accept mnemic causation in psychology pro 
tern, and therefore reject parallelism, since there is no 
good ground for admitting mnemic causation in physics. 

It is perhaps worth while to observe that mnemic causa- 
tion is what led Bergson to deny that there is causation 
at all in the psychical sphere. He points out, very truly, 
that the same stimulus, repeated, does not have the same 
consequences, and he argues that this is contrary to the 
maxim, " same cause, same effect." It is only necessary, 
however, to take account of past occurrences arid include 
them with the cause, in order to re-establish the maxim, 


and the possibility of psychological causal laws. The 
metaphysical conception of a cause lingers in our manner 
of viewing causal laws : we want to be able to feel a 
connection between cause and effect, and to be able to 
imagine the cause as " operating/' This makes us unwill- 
ing to regard causal laws as merely observed uniformities 
of sequence ; yet that is all that science has to offer. 
To ask why such-and-such a kind of sequence occurs is 
either to ask a meaningless question, or to demand some 
more general kind of sequence which includes the one in 
question. The widest empirical laws of sequence known 
at any time can only be " explained " in the sense of being 
subsumed by later discoveries under wider laws ; but 
these wider laws, until they in turn are subsumed, will 
remain brute facts, resting solely upon observation, not 
upon some supposed inherent rationality. 

There is therefore no a priori objection to a causal law 
in which part of the cause has ceased to exist. To argue 
against such a law on the ground that what is past cannot 
operate now, is to introduce the old metaphysical notion 
of cause, for which science can find no place. The only 
reason that could be validly alleged against mnemic 
causation would be that, in fact, all the phenomena can 
be explained without it. They are explained without 
it by Semon's " engram," or by any theory which regards 
the results of experience as embodied in modifications of 
the brain and nerves. But they are not explained, unless 
with extreme artificiality, by any theory which regards 
the latent effects of experience as psychical rather than 
physical. Those who desire to make psychology as far 
as possible independent of physiology would do well, it 
seems to me, if they adopted mnemic causation. For 
my part, ^however, I have no such desire, and I shall 


therefore endeavour to state the grounds which occur 
to me in favour of some such view as that of the 
" engram." 

One of the first points to be urged is that mnemic 
phenomena are just as much to be found in physiology as 
in psychology. They are even to be found in plants, 
as Sir Francis Darwin pointed out (cf . Semon, Die Mneme, 
2nd edition, p. 28 n.). Habit is a characteristic of the body 
at least as much as of the mind. We should, therefore, 
be compelled to allow the intrusion of mnemic causation, 
if admitted at all, into non-psychological regions, which 
ought, one feels, to be subject only to causation of the 
ordinary physical sort. The fact is that a great deal of 
what, at first sight, distinguishes psychology from physics 
is found, on examination, to be common to psychology 
and physiology ; this whole question of the influence of 
experience is a case in point. Now it is possible, of course, 
to take the view advocated by Professor J. S. Haldane, 
who contends that physiology is not theoretically reducible 
to physics and chemistry. 1 But the weight of opinion 
among physiologists appears to be against him on this 
point ; and we ought certainly to require very strong 
evidence before admitting any such breach of continuity 
as between living and dead matter. The argument from 
the existence of mnemic phenomena in physiology must 
therefore be allowed a certain weight against the hypo- 
thesis that mnemic^causation is ultimate. 

The argument from the connection of brain-lesions 
with loss of memory is not so strong as it looks, though 

See his The New Physiology and Other Addresses, Griffin, 1919; 
also the symposium, " Are Physical, Biological and Psychological 
Categories Irreducible ? " in Life and Finite Individuality, edited 
for the Aristotelian Society, with an Introduction. By H. Wildon 
Carr, Williams & Norgate, 1918. 


it has also some weight. What we know is that memory, 
and mnemic phenomena generally, can be disturbed or 
destroyed by changes in the brain. This certainly proves 
that the brain plays an essential part in the causation of 
memory, but does not prove that a certain state of the 
brain is, by itself, a sufficient condition for the existence 
of memory. Yet it is this last that has to be proved. 
The theory of the engram, or any similar theory, has to 
maintain that, given a body and brain in a suitable state, 
a man will have a certain memory, without the need of 
any further conditions. What is known, however, is only 
that he will not have memories if his body and brain are 
not in a suitable state. That is to say, the appropriate 
state of body and brain is proved to be necessary for 
memory, but not to be sufficient. So far, therefore, as 
our definite knowledge goes, memory may require for its 
causation a past occurrence as well as a certain present 
state of the brain. 

In order to prove conclusively that mnemic phenomena 
arise whenever certain physiological conditions are ful- 
filled, we ought to be able actually to see differences 
between the brain of a man who speaks English and that 
of a man who speaks French, between the brain of a man 
who has seen New York and can recall it, and that of a 
man who has never seen that city. It may be that the 
time will come when this will be possible, but at present 
we are very far removed from it. At present, there is, so 
far as I am aware, no good evidence that every difference 
between the knowledge possessed by A and that possessed 
by B is paralleled by some difference in their brains. We 
may believe that this is the case, but if we do, our belief 
is based upon analogies and general scientific maxims, 
not upon any foundation of detailed observation. I 


am myself inclined, as a working hypothesis, to adopt 
^he belief in question, and to hold that past experience 
only affects present behaviour through modifications 
of physiological structure. But the evidence seems not 
quite conclusive, so that I do not think we ought to for- 
get the other hypothesis, or to reject entirely the possi- 
bility that mnemic causation may be the ultimate explana- 
tion of mnemic phenomena. I say this, not because I 
think it likely that mnemic causation is ultimate, but 
merely because I think it possible, and because it often 
turns out important to the progress of science to remem- 
ber hypotheses which have previously seemed improbable. 




THE traditional conception of cause and effect is one 
which modern science shows to be fundamentally erroneous, 
and requiring to be replaced by a quite different notion, 
that of laws of change. In the traditional conception, 
a particular event A caused a particular event B, and 
by this it was implied that, given any event B, some 
earlier event A could be discovered which had a relation 
to it, such that 

(1) Whenever A occurred, it was followed by B ; 

(2) In this sequence, there was something " neces- 

sary/' not a mere de facto occurrence of A 
first and then B. 

The second point is illustrated by the old discussion 
as to whether it can be said that day causes night, on 
the ground that day is always followed by night. The 
orthodox answer was that day could not be called the 
cause of night, because it would not be followed by night 
if the earth's rotation were to cease, or rather to grow so 
slow that one complete rotation would take a year. A 
cause, it was held, must be such that under no conceivable 
circumstances could it fail to be followed by its effect. 


As a matter of fact, such sequences as were sought by 
believers in the traditional form of causation have not 
so far been found in nature. Everything in nature is 
apparently in a state of continuous change, 1 so that 
what we call one " event " turns out to be really a process. 
If this event is to cause another event, the two will have 
to be contiguous in time ; for if there is any interval 
between them, something may happen during that interval 
to prevent the expected effect. Cause and effect, therefore, 
will have to be temporally contiguous processes. It is 
difficult to believe, at any rate where physical laws are 
concerned, that the earlier part of the process which 
is the 'cause can make any difference to the effect, so 
long as the later part of the process which is the cause 
remains unchanged. Suppose, for example, that a man 
dies of arsenic poisoning, we say that his taking arsenic 
was the cause of death. But clearly the process by which 
he acquired the arsenic is irrelevant : everything that 
happened before he swallowed it may be ignored, since 
it cannot alter the effect except in so far as it alters 
his condition at the moment of taking the dose. But 
we may go further : swallowing arsenic is not really 
the proximate cause of death, since a man might be shot 
through the head immediately after taking the dose, and 
then it would not be of arsenic that he would die. The 
arsenic produces certain physiological changes, which take 
a finite time before they end in death. The earlier parts 
of these changes can be rilled out in the same way as 
we can rule out the process by which the arsenic was 

1 The theory of quanta suggests that the continuity is only 
apparent. If so, we shall be able theoretically to reach events 
which are not processes. But in what is directly obser /able there 
is still apparent continuity, which justifies the above remarks for 
the present. 


acquired. Proceeding in this way, we can shorten the 
process ,whieh we are calling the cause more and more. 
Similarly we shall have to shorten the effect. It may 
happen that immediately after the man's death his body 
is blown to pieces by a bomb. We cannot say what will 
happen after the man's death, through merely knowing 
that he has died as the result of arsenic poisoning. Thus, 
if we are to take the cause as one event and the effect 
as another, both must be shortened indefinitely. The 
result is that we merely have, as the embodiment of 
our causal law, a certain direction of change at each 
moment. Hence we are brought to differential equations 
as embodying causal laws. A physical law does not 
say " A will be followed by B," but tells us what accelera- 
tion a particle will have under given circumstances, i.e. 
it tells us how the particle's motion is changing at each 
moment, not where the particle will be at some future 

Laws embodied in differential equations may possibly 
be exact, but cannot be known to be so. All that we 
can know empirically is approximate and liable to ex- 
ceptions ; the exact laws that are assumed in physics are 
known to be somewhere near the truth, but are not known 
to be true just as they stand. The laws that we actually 
know empirically have the form of the traditional causal 
laws, except that they are not to be regarded as universal 
or necessary. " Taking arsenic is followed by death " is 
a good empirical generalization ; it may have exceptions, 
but they will be rare. As against the professedly exact 
laws of physics, such empirical generalizations have the 
advantage that they deal with observable phenomena. 
We cannot observe infinitesimals, whether in time or 
space ; we do not even know whether time and space 


are infinitely divisible. Therefore rough empirical 
generalizations have a definite place in science, in spite 
of not being exact or universal. They are the data 
for more exact laws, and the grounds for believing that 
they are usually true are stronger than the grounds for 
believing that the more exact laws are always true. 

Science starts, therefore, from generalizations of the 
form, " A is usually followed by B." This is the nearest 
approach that can be made to a causal law of the traditional 
sort. It may happen in any particular instance that A 
is always followed by B, but we cannot know this, since 
we cannot foresee all the perfectly possible circumstances 
that -might make the sequence fail, or know that none 
of them will actually occur. If, however, we know of a 
very large number of cases in which A is followed by B, 
and few or none in which the sequence fails, we shall in 
practice be justified in saying " A causes B," provided 
we do not attach to the notion of cause any of the meta- 
physical superstitions that have gathered about the word. 

There is another point, besides lack of universality 
and necessity, which it is important to realize as regards 
causes in the above sense, and that is the lack of uniqueness. 
It is generally assumed that, given any event, there is 
some one phenomenon which is the cause of the event 
in question. This seems to be a mere mistake. Cause, 
in the only sense in which it can be practically applied, 
means " nearly invariable antecedent." We cannot in 
practice obtain an antecedent which is quite invariable, 
for this would require us to take account of the whole 
universe, since something not taken account of may 
prevent the expected effect. We cannot distinguish, 
among nearly invariable antecedents, one as the cause, 
and the others as merely its concomitants : the attempt 


to do this depends upon a notion of cause which is derived 
from will, and will (as we shall see later) is not at all 
the sort of thing that it is generally supposed to be, nor 
is there any reason to think that in the physical world 
there is anything even remotely analogous to what will 
is supposed to be. If we could find one antecedent, and 
only one, that was quite invariable, we could call that 
one the cause without introducing any notion derived 
from mistaken ideas about will. But in fact we cannot 
find any antecedent that we know to be quite invariable, 
and we can find many that are nearly so. For example, 
men leave a factory for dinner when the hooter sounds 
at twelve o'clock. You may say the hooter is the cause 
of their leaving. But innumerable other hooters in 
other factories, which also always sound at twelve o'clock, 
have just as good a right to be called the cause. Thus 
every event has many nearly invariable antecedents, 
and therefore many antecedents which may be called 
its cause. 

The laws of traditional physics, in the form in which 
they deal with movements of matter or electricity, have 
an apparent simplicity which somewhat conceals the 
empirical character of what they assert. A piece of mat- 
ter, as it is known empirically, is not a single existing 
thing, but a system of existing things. When several 
people simultaneously see the same table, they all see 
something different; therefore "the" table, which they 
are supposed all to see, must be either a hypothesis or a 

construction. "The" table is to be neutral as between 


different observers : it does not favour the aspect seen by 
one man at the expense of that seen by another. It was 
natural, though to my mind mistaken, to regard the " real " 
table as the common cause of all the appearances which 



the table presents (as we say) to different observers. But 
why should we suppose that there is some one common 
cause of all these appearances? As we have just seen, the 
notion of " cause " is not so reliable as to allow us to 
infer the existence of something that, by its very nature, 
can never be observed. 

Instead of looking for an impartial source, we can 
secure neutrality by the equal representation of all parties. 
Instead of supposing that there is some unknown cause, 
the " real " table, behind the different sensations of those 
who are said to be looking at the table, we may take the 
whole set of these sensations (together possibly with 
certain other particulars) as actually being the table. 
That is to say, the table which is neutral as between 
different observers (actual and possible) is the set of 
all those particulars which would naturally be called 
"aspects" of the table from different points of 
view. (This is a first approximation, modified later.) 

It may be said : If there is no single existent which is 
the source of all these " aspects/' how are they collected 
together ? The answer is simple : Just as they would 
be if there were such a single existent. The supposed 
" real " table underlying its appearances is, in any case, 
not itself perceived, but inferred, and the question whether 
such-and-such a particular is an " aspect " of this table 
is only to be settled by the connection of the particular in 
question with the one or more particulars by which the 
table is defined. That is to say, even if we assume a 
" real " table, the particulars which are its aspects have to 
be collected together by their relations to each other, not to 
it f since it is merely inferred from them. We have only, 
therefore, to notice how they are collected together, and 
we can then keep the collection without assuming any 


" real " table as distinct from the collection. When 
different people see what they call the same table, they 
see things which are not exactly the same, owing to 
"difference of point of view, but which are sufficiently alike 
to be described in the same words, so long as no great 
accuracy or minuteness is sought. These closely similar 
particulars are collected together by their similarity 
primarily and, more correctly, by the fact that they 
are related to each other approximately according to the 
laws of perspective and of reflection and diffraction of 
light. I suggest, as a first approximation, that these 
particulars, together with such correlated others as are 
unperceived, jointly are the table ; and that a similar 
definition applies to all physical objects. 1 

In order to eliminate the reference to our perceptions, 
which introduces an irrelevant psychological suggestion, 
I will take a different illustration, namely, stellar photo- 
graphy. A photographic plate exposed on a clear night 
reproduces the appearance of the portion of the sky 
concerned, with more or fewer stars according to the 
power of the telescope that is being used. Each separate 
star which is photographed produces its separate effect 
on the plate, just as it would upon ourselves if we were 
looking at the sky. If we assume, as science normally 
does, the continuity of physical processes, we are forced 
to conclude that, at the place where the plate is, and at 
all places between it and a star which it photographs, 
something is happening which is specially connected 
with that star. In the days when the aether was less 
in doubt, we should have said that what was happening 
was a certain kind of transverse vibration in the aether. 

1 See Our Knowledge of the External World (Allen & Unwin), 
chaps, iii and iv. 


But it is not necessary or desirable to be so explicit : 
all that we need say is that something happens which is 
specially connected with the star in question. It must 
be something specially connected with that star, since 
that star produces its own special effect upon the plate. 
Whatever it is must be the end of a process which starts 
from the star and radiates outwards, partly on general 
grounds of continuity, partly to account for the fact 
that light is transmitted with a certain definite velocity. 
We thus arrive at the conclusion that, if a certain star 
is visible at a certain place, or could be photographed 
by a sufficiently sensitive plate at that place, something 
is happening there which is specially connected with 
that star. Therefore in every place at all times a vast 
multitude of things must be happening, namely, at least 
one for every physical object which can be seen or photo- 
graphed from that place. We can classify such happenings 
on either of two principles : 

(1) We can collect together all the happenings 

in one place, as is done by photography so far 
as light is concerned ; 

(2) We can collect together all the happenings, in 

different places, which are connected in the way 
that common sense regards as being due to 
their emanating from one object. 

Thus, to return to the stars, we can collect together 

(1) All the appearances of different stars in a given 

place, or, 

(2) All the appearances of a given star in different 



But when I speak of " appearances/' I do so only for 
brevity : I do not mean anything that must " appear " 
to somebody, but only that happening, whatever it 
may^ be, which is connected, at the place in question, 
with a given physical object according to the old ortho- 
dox theory, it would be a transverse vibration in the 
aether. Like the different appearances of the table to 
a number of simultaneous observers, the different particu- 
lars that belong to one physical object are to be collected 
together by continuity and inherent laws of correlation, 
not by their supposed causal connection with an unknown 
assumed existent called a piece of matter, which would 
be a mere Unnecessary metaphysical thing in itself. 
A piece of matter, according to the definition that I 
propose, is, as a first approximation, 1 the collection of all 
those correlated particulars which would normally be 
regarded as its appearances or effects in different places. 
Some further elaborations are desirable, but we can ignore 
them for the present. I shall return to them at the end 
of this lecture. 

, According to the view that I am suggesting, a physical 
object or piece of matter is the collection of all those 
correlated particulars which would be regarded by common 
' sense as its effects or appearances in different places. On 
the other hand, all the happenings in a given place represent 
what common sense would regard as the appearances of 
a number of different objects as viewed from that place. 
All the happenings in one place may * be regarded as 
the view of the world from that place. I shall call the 
view of the world from a given place a " perspective." 
A photograph represents a perspective. On the other 

1 The exact definition of a piece of matter as a construction 
will be given later. 


hand, if photographs of the stars were taken in all points 
throughout space, and in all such photographs a certain 
star, say Sirius, were picked out whenever it appeared, all 
the different appearances of Sirius, taken together, would 
represent Sirius. For the understanding of the difference 
between psychology and physics it is vital to understand 
these two ways of classifying particulars, namely : 

(1) According to the place where they occur ; 

(2) According to the system of correlated par- 

ticulars in different places to which they 
belong, such system being defined as a physical 

Given a system of particulars which is a physical object, 
I shall define that one of the system which is in a given 
place (if any) as the " appearance of that object in that 

When the appearance of an object in a given place 
changes, it is found that one or other of two things occurs. 
The two possibilities may be illustrated by an example. 
You are in a room with a man, whom you see : you may 
cease to see him either by shutting your eyes or by his 
going out of the room. In the first case, his appearance 
to other people remains unchanged ; in the second, his 
appearance changes from all places. In the first case, you 
say that it is not he who has changed, but your eyes ; 
in the second, you say that he has changed. Generalizing, 
we distinguish 

(i) Cases in which only certain appearances of the 
object change, while others, and especially 
appearances from places very near to the 
object, do not change ; 


(2) Cases where all, or almost all, the appear- 
ances of the object undergo a connected 

In the first case, the change is attributed to the medium 
between the object and the place ; in the second, it is 
attributed to the object itself. 1 

It is the frequency of the latter kind of change, and 
the comparatively simple nature of the laws governing 
the simultaneous alterations of appearances in such 
cases, that have made it possible to treat a physical 
object as one thing, and to overlook the fact that it is 
a system of particulars. When a number of people at 
a theatre watch an actor, the changes in their several 
perspectives are so similar and so closely correlated that 
all are popularly regarded as identical with each other 
and with the changes of the actor himself. So long as all 
the changes in the appearances of a body are thus correlated 
there is no pressing prima facie need to break up the 
system of appearances, or to realize that the body in 
question is not really one thing but a set of correlated 
particulars. It is especially and primarily such changes 
that physics deals with, i.e. it deals primarily with processes 
in which the unity of a physical object need not be broken 
up because all its appearances change simultaneously 
according to the same law or, if not all, at any rate 
all from places sufficiently near to the object, with in- 
creasing accuracy as we approach the object. 

The changes in appearances of an object which are 
due to changes in the intervening medium will not affect, 
or will affect only very slightly, the appearances from 

1 The application of this distinction to motion raises complica- 
tions due to relativity, but we may ignore these for our present 


places close to the object. If the appearances from 
sufficiently neighbouring places are either wholly un- 
changed, or changed to a diminishing extent which has 
zero for its limit, it is usually found that the changes 
can be accounted for by changes in objects which are 
between the object in question and the places from which 
its appearance has changed appreciably. Thus physics 
is able to reduce the laws of most changes with which it 
deals to changes in physical objects, and to state most of 
its fundamental laws in terms of matter. It is only in those 
cases in which the unity of the system of appearances 
constituting a piece of matter has to be broken up, that 
the statement of what is happening cannot be made 
exclusively in terms of matter. The whole of psychology, 
we shall find, is included among such cases ; hence their 
importance for our purposes. 

We can now begin to understand one of the fundamental 
differences between physics and psychology. Physics 
treats as a unit the whole system of appearances of a 
piece of matter, whereas psychology is interested in 
certain of these appearances themselves. Confining our- 
selves for the moment to the psychology of perceptions, we 
observe that perceptions are certain of the appearances 
of physical objects. From the point of view that we 
have been hitherto adopting, we might define them as the 
appearances of objects at places from which sense-organs 
and the suitable parts of the nervous system form part 
of the " intervening medium. Just as & photographic 
plate receives a different impression of a cluster of stars 
when a telescope is part of the intervening medium, so 
a brain receives a different impression when an eye and 
an optic nerve are part of the intervening medium. 
An impression due to this sort of intervening medium ; 


is called a perception, and is interesting to psychology on 
its own account, not merely as one of the set of correlated 
particulars which is the physical object of which (as we 
say) we are having a perception. 

We spoke earlier of two ways of classifying particulars. 
One way collects together the appearances commonly 
regarded as a given object from different places ; this is, 
broadly speaking, the way of physics, leading to the con- 
struction of physical objects as sets of such appearances. 
The other way collects together the appearances of 
different objects from a given place, the result being what 
we call a perspective. In the particular case where 
the place concerned is a human brain, the perspective 
belonging to the place consists of all the perceptions of 
a certain man at a given time. Thus classification by 
perspectives is relevant to psychology, and is essential 
in defining what we mean by one mind. 

I do not wish to suggest that the way in which I have 
been defining perceptions is the only possible way, or 
even the best way. It is the way that arose naturally 
out of our present topic. But when we approach psy- 
chology from a more introspective standpoint, we have to 
distinguish sensations and perceptions, if possible, from 
other mental occurrences, if any. We have also to con- 
sider the psychological effects of sensations, as opposed 
to their physical causes and correlates. These problems 
are quite distinct from those with which we have been 
concerned in the present lecture, and I shall not deal 
with them until a later stage. 

It is clear that psychology is concerned essentially with 
actual particulars, not merely with systems of particulars. 
In this it differs from physics, which, broadly speaking, 
is concerned with the cases in which all the particulars 


which make up one physical object can be treated as a 
single causal unit, or rather the particulars which are 
sufficiently near to the object of which they are appearances 
can be so treated. The laws which physics seeks can, 
broadly speaking, be stated by treating such systems of 
particulars as causal units. The laws which psychology 
seeks cannot be so stated, since the particulars themselves 
are what interests the psychologist. This is one of the 
fundamental differences between physics and psychology ; 
and to make it clear has been the main purpose of this 

I will conclude with an attempt to give a more precise 
definition of a piece of matter. The appearances of a 
piece of matter from different places change partly 
according to intrinsic laws (the laws of perspective, in 
the case of visual shape), partly according to the nature 
of the intervening medium fog, blue spectacles, telescopes, 
microscopes, sense-organs, etc. As we approach nearer 
to the object, the effect of the intervening medium grows 
less. In a generalized sense, all the intrinsic laws of 
change of appearance may be called " laws of perspective." 
Given any appearance of an object, we can construct 
hypothetically a certain system of appearances to which 
the appearance in question would belong if the laws of 
perspective alone were concerned. If we construct this 
hypothetical system for each appearance of the object 
in turn, the system corresponding to a given appearance 
x will be independent of any distortion due to the medium 
beyond x, and will only embody such distortion as is due 
to the medium between % and the object. Thus, as the 
appearance by which our hypothetical system is defined 
is moved nearer and nearer to the object, the hypo- 
thetical system of appearances defined by its means 


embodies less and less of the effect of the medium. The 
different sets of appearances resulting from moving x 
nearer and nearer to the object will approach to a 
limiting set, and this limiting set will be that system 
of appearances which the object would present if the 
laws of perspective alone were operative and the medium 
exercised no distorting effect. This limiting set of 
appearances may be defined, for purposes of physics, as 
the piece of matter concerned. 


ONE of the main purposes of these lectures is to give 
grounds for the belief that the distinction between mind 
and matter is not so fundamental as is commonly supposed. 
In the preceding lecture I dealt in outline with the physical 
side of this problem. I attempted to show that what 
we call a material object is not itself a substance, but 
is a system of particulars analogous in their nature to 
sensations, and in fact often including actual sensations 
among their number. In this way the stuff ot which 
physical objects are composed is brought into relation 
with the stuff of which part, at least, of our mental life 
is composed. 

There is, however, a converse task which is equally 
necessary for our thesis, and that is, to show that the 
stuff of our mental life is devoid of many qualities which 
it is commonly supposed to have, and is not possessed 
of any attributes which make it incapable of forming 
part of the world of matter. In the present lecture 
I shall begin the arguments for this view. 

Corresponding to the supposed duality of matter and 
mind, there are, in orthodox psychology, two w^ys of 
knowing what exists. One of these, the way of sensation 
and external perception, is supposed to furnish data for 



our knowledge of matter, the other, called " introspection," 
is supposed to furnish data for knowledge of our mental 
processes. To common sense, this distinction seems 
clear and easy. When you see a friend coming along 
the street, you acquire knowledge of an external, physical 
fact ; when you realize that you are glad to meet him, 
you acquire knowledge of a mental fact. Your dreams 
and memories and thoughts, of which you are often 
conscious, are mental facts, and the process by which you 
become aware of them seems to be different from sensa- 
tion. Kant calls it the " inner sense " ; sometimes it is 
spoken of as " consciousness of self " ; but its commonest 
name in modern English psychology is " introspection." 
It is this, supposed method of acquiring knowledge of our 
mental processes that I wish to analyse and examine in 
this lecture. 

I will state at the outset the view which I shall aim at 
establishing. I believe that the stuff of our mental life, 
as opposed to its relations and structure, consists wholly 
of sensations and images. Sensations are connected with 
matter in the way that I tried to explain in Lecture V, 
i.e. each is a member of a system which is a certain 
physical object. Images, though they usually have 
certain characteristics, especially lack of vividness, that 
distinguish them from sensations, are not invariably so 
distinguished, and cannot therefore be defined by these 
characteristics. Images, as opposed to , sensations, can 
only be defined by their different causation : they are 
caused by association with a sensation, not by a stimulus 
external to the nervous system or perhaps one should 
say external to the brain, where the higher animals are 
concerned. The occurrence of a sensation or image 
does not in itself constitute knowledge, but any sensation 


or image may come to be known if the conditions are 
suitable. When a sensation like' the hearing of a clap 
of thunder is normally correlated with closely similar 
sensations in our neighbours, we regard it as giving know- 
ledge of the external world, since we regard the whole 
set of similar sensations as due to a common external 
cause. But images and bodily sensations are not so 
correlated. Bodily sensations can be brought into a 
correlation by physiology, and thus take their place 
ultimately among sources of knowledge of the physical 
world. But images cannot be made to fit in with the 
simultaneous sensations and images of others. Apart 
from their hypothetical causes in the brain, they have 
a causal connection with physical objects, through the 
fact that they are copies of past sensations ; but the 
physical objects with which they are thus connected 
are in the past, not in the present. These images remain 
private in a sense in which sensations are not. A sensation 
seems to give us knowledge of a present physical object, 
while an image does not, except when it amounts to a 
hallucination, and in this case the seeming is deceptive. 
Thus the whole context of the two occurrences is different. 
But in themselves they do not differ profoundly, and 
there is no reason to invoke two different ways of knowing 
for the one and for the other. Consequently introspection 
as a separate kind of knowledge disappears. 

The criticism of introspection has been in the main the 
work of American psychologists. I will begin by sum- 
marizing an article which seems to me to afford a good 
specimen of their arguments, namely, " The Case against 
Introspection," by Knight Dunlap (Psychological Review, 
vol xix, No. 5, pp. 404-413, September, 1912). After a 
few historical quotations, he comes to two modern 


defenders of introspection, Stout and James. He quotes 
from Stout such statements as the following : " Psychical 
states as such become objects only when we attend to them 
in an introspective way. Otherwise they are not them- 
selves objects, but only constituents of the process by 
which objects are recognized " (Manual, 2nd edition, 
p. 134. The word " recognized " in Dunlap's quotation 
should be "cognized/') "The object itself can never 
be identified with the present modification of the in- 
dividual's consciousness by which it is cognized " (ib. 
p. 60). This is to be true even when we are thinking 
about modifications of our own consciousness; such 
modifications are to be always at least partially distinct 
from the conscious experience in which we think of them. 
At this point I wish to interrupt the account of Knight 
Dunlap's article in order to make some observations on 
my own account with reference to the above quotations 
from Stout. In the first place, the conception of " psy- 
chical states " seems to me one which demands analysis 
of a somewhat destructive character. This analysis I 
shall give in later lectures as regards cognition ; I have 
already given it as regards desire. In the second place, 
the conception of " objects " depends upon a certain view 
as to cognition which I believe to be wholly mistaken, 
namely, the view which I discussed in my first lecture 
in connection with Brentano. In this view a single 
cognitive occurrence contains both content and object, 
the content being essentially mental, while the object 
is physical except in introspection and abstract thought. 
I have already criticized this view, and will not dwell 
upon it now, beyond saying that " the process by which 
objects are cognized " appears to be a very slippery 
phrase. When we "see a table/' as common sense 
would say, the table as a physical object is not the 


" object " (in the psychological sense) of our perception. 
Our perception is made up of sensations, images and be- 
liefs, but the supposed " object " is something inferential, 
externally related, not logically bound up with what is 
occurring in us. This question of the nature of the object 
also affects the view we take of self -consciousness. 
Obviously, a " conscious experience " is different from 
a physical object ; therefore it is natural to assume that 
a thought or perception whose object is a conscious ex- 
perience must be different from a thought or perception 
whose object is a physical object. But if the relation 
to the object is inferential and external, as I maintain, 
the difference between two thoughts may bear very little 
relation to the difference between their objects. And 
to speak of " the present modification of the individual's 
consciousness by which an object is cognized " is to 
suggest that the cognition of objects is a far more direct 
process, far more intimately bound up with the objects, 
than I believe it to be. All these points will be amplified 
when we come to the analysis of knowledge, but it is 
necessary briefly to state them now in order to suggest 
the atmosphere in which our analysis of " introspection " 
is to be carried on. 

Another point in which Stout's remarks seem to me to 
suggest what I regard as mistakes is his use of " conscious- 
ness." There is a view which is prevalent among psycho- 
logists, to the effect that one can speak of " a conscious 
experience " in a curious dual sense, meaning, on the 
one hand, an experience which is conscious of something, 
and, on the other hand, an experience which has some 
intrinsic nature characteristic of what is called " conscious- 
ness." That is to say, a " conscious experience " is 
characterized on the one hand by relation to its object 


and on the other hand by being composed of a certain 
peculiar stuff, the stuff of " consciousness." And in 
many authors there is yet a third confusion : a " conscious 
experience," in this third sense, is an experience of which 
we are conscious. All these, it seems to me, need to 
be clearly separated. To say that one occurrence is 
" conscious " of another is, to my mind, to assert an 
external and rather remote relation between them. I 
might illustrate it by the relation of uncle and nephew : 
a man becomes an uncle through no effort of his own, 
merely through an occurrence elsewhere. Similarly, 
when you are said to be " conscious " of a table, the 
question whether this is really the case cannot be decided 
by examining only your state of mind : it is necessary 
also to ascertain whether your sensation is having those 
correlates which past experience causes you to assume, 
or whether the table happens, in this case, to be a mirage. 
And, as I explained in my first lecture, I do not believe 
that there is any " stuff " of consciousness, so that there 
is no intrinsic character by which a " conscious " experi- 
ence pould be distinguished from any other. 

After these preliminaries, we can return to Knight 
Dunlap's article. His criticism of Stout turns on the 
difficulty of giving any empirical meaning to such notions 
as the " mind " or the " subject " ; he quotes from Stout 
the sentence : " The most important drawback is that 
the mind, in watching its own workings, must necessarily 
have its attention divided between two objects," and 
he concludes : " Without question, Stout is bringing in 
here illicitly the concept of a single observer, and his 
introspection does not provide for the observation of 
this observer ; for the process observed and the observer 
are distinct " (p. 407). The objections to any theory 



which brings in the single observer were considered in 
Lecture I, and were acknowledged to be cogent. In so 
far, therefore, as Stout's theory oi introspection rests 
upon this assumption, we are compelled to reject it. 
But it is perfectly possible to believe in introspection 
without supposing that there is a single observer. 

William James's theory of introspection, which Dunlap 
next examines, does not assume a single observer. It 
changed after the publication of his Psychology, in 
consequence of his abandoning the dualism of thought 
and things. Dunlap summarizes his theory as follows : 

" The essential points in James's scheme of consciousness 
are subject, object, and a knowing of the object by the subject. 
The difference between James's scheme and other schemes 
involving the same terms is that James considers subject 
and object to be the same thing, but at different times. 
In order to satisfy this requirement James supposes a 
realm of existence which he at first called * states of 
consciousness ' or ' thoughts,' and later, ' pure experi- 
ence/ the latter term including both the ' thoughts ' 
and the ' knowing.' This scheme, with all its magnifi- 
cent artificiality, James held on to until the end, simply 
dropping the term consciousness and the dualism between 
the thought and an external reality " (p. 409). 

He adds : "All that James's system really amounts 
to is the acknowledgment that a succession of things 
are known, and that they are known by something. This 
is all any one can claim, except for the fact that the things 
are known together, and that the knower for the different 
items is one and the same " (ib.). 

In this statement, to my mind, Dunlap concedes far 
more than James did in his later theory. I see no reason 
to suppose that " the knower for different items is one 


and the same/' and I am convinced that this proposition 
could not possibly be ascertained except by introspection 
of the sort that Dunlap rejects. The first of these points 
must wait until we come to the analysis of belief : the 
second must be considered now. Dunlap's view is that 
there is a dualism of subject and object, but that the 
subject can never become object, and therefore there 
is no awareness of an awareness. He says in discussing 
the view that introspection reveals the occurrence of 
knowledge : " There can be no denial of the existence 
of the thing (knowing) which is alleged to be known or 
observed in this sort of ' introspection/ The allegation 
that the knowing is observed is that which may be denied. 
Knowing there certainly is ; known, the knowing certainly 
is not " (p. 410). And again : " I am never aware of 
an awareness " (ib.). And on the next page : " It may 
sound paradoxical to say that one cannot observe the 
process (or relation) of observation, and yet may be 
certain that there is such a process : but there is really 
no inconsistency in the saying. How do I know that 
there is awareness ? By being aware of something. 
There is no meaning in the term ' awareness ' which is 
not expressed in the statement ' I am aware of a colour 
(or what-not)/ \" 

But the paradox cannot be so lightly disposed of. The 
statement " I api aware of a colour " is assumed by 
Knight Dunlap to be known to be true, but he does not 
explain how it comes to be known. The argument 
against him is not conclusive, since he may be able to 
show some valid way of inferring our awareness. But 
he does not suggest any such way. There is nothing 
odd in the hypothesis of beings which are aware of objects, 
but not of their own awareness ; it is, indeed, highly 


probable that young children and the higher animals 
are such beings. But such beings cannot make the state- 
ment " I am aware of a colour/' which we can make. We 
have, therefore, some knowledge which they lack. It is 
necessary to Knight Dunlap's position to maintain that 
this additional knowledge is purely inferential, but he 
makes no attempt to show how the inference is possible. 
It may, of course, be possible, but I cannot see how. To 
my mind the fact (which he admits) that we know there is 
awareness, is all but decisive against his theory, and in 
favour of the view that we can be aware of an awareness. 

Dunlap asserts (to return to James) that the real ground 
for James's original belief in introspection was his belief 
in two sorts of objects, namely, thoughts and things. 
He suggests that it was a mere inconsistency on James's 
part to adhere to introspection after abandoning the 
dualism of thoughts and things. I do not wholly agree 
with this view, but it is difficult to disentangle the difference 
as to introspection from the difference as to the nature 
of knowing. Dunlap suggests (p. 411) that what is called 
introspection really consists of awareness of " images," 
visceral sensations, and so on. This view, in essence, 
seems to me sound. But then I hold that knowing itself 
consists of such constituents suitably related, and that 
in being aware of them we are sometimes being aware 
of instances of knowing. For this reason, much as I 
agree with his view as to what are the objects of which 
there is awareness, I cannot wholly agree with his con- 
clusion as to the impossibility of introspection. 

The behaviourists have challenged introspection even 
more vigorously than Knight Dunlap, and have gone so 
far as to deny the existence of images. But I think 
that they have confused various things which are very 


commonly confused, and that it is necessary to make 
several distinctions before we can arrive at what is 
true and what false in the criticism of introspection. 

*.'! wish to distinguish three distinct questions, any one 
of which may be meant when we ask whether introspection 
is a source of knowledge. The three questions are as 
follows : 

(1) Can we observe anything about ourselves which 
we cannot observe about other people, or is everything 
we can observe public, in the sense that another could 
also observe it if suitably placed ? 

(2) Does everything that we can observe obey the laws 
of physics and form part of the physical world, or can 
we observe certain things that lie outside physics ? 

(3) Can we observe anything which differs in its intrinsic 
nature from the constituents of the physical world, or 
is everything that we can observe composed of elements 
intrinsically similar to the constituents of what is called 
matter ? 

* Any one of these three questions may be used to define 
introspection. I should favour introspection in the 
sense of the first question, i.e. I think that some of the 
things we observe cannot, even theoretically, be observed 
by any one else. The second question, tentatively and 
for the present, I should answer in favour of introspection ; 
I think that images, in the actual condition of science, 
cannot be brought under the causal laws of physics, 
though perhaps ultimately they may be. The third 
question I should answer adversely to introspection : 
I think that observation shows us nothing that is not 
composed of sensations and images, and that images 
differ from sensations in their causal laws, not intrinsically. 
I shall deal with the three questions successively. 


(i) Publicity or privacy of what is observed. Confining 
ourselves, for the moment, to sensations, we find that 
there are different degrees of publicity attaching to 
different sorts of sensations. If you feel a toothache 
when the other people in the room do not, you are in 
no way surprised ; but if you hear a clap of thunder 
when they do not, you begin to be alarmed as to your 
mental condition. Sight and hearing are the most public 
of the senses ; smell only a trifle less so ; touch, again, 
a trifle less, since two people can only touch the same 
spot successively, not simultaneously. Taste has a sort 
of semi-publicity, since people seem to experience similar 
taste-sensations when they eat similar foods ; but the 
publicity is incomplete, since two people cannot eat 
actually the same piece of food. 

But when we pass on to bodily sensations headache, 
toothache, hunger, thirst, the feeling of fatigue, and 
so on we get quite away from publicity, into a region 
where other people can tell us what they feel, but we 
cannot directly observe their feeling. As a natural result 
of this state of affairs, it has come to be thought that 
the public senses give us knowledge of the outer world, 
while the private senses only give us knowledge as to our 
own bodies. As regards privacy, all images, of whatever 
sort, belong with the sensations which only give knowledge 
of our own bodies, i.e. each is only observable by one 
observer. This is the reason why images of sight and 
hearing are more obviously different from sensations of 
sight and hearing than images of bodily sensations are 
from bodily sensations ; and that is why the argument 
in favour of images is more conclusive in such cases as 
sight and hearing than in such cases as inner speech. 

The whole distinction of privacy and publicity, however, 


so long as we confine ourselves to sensations, is one of 
degree, not of kind. No two people, there is good em- 
pirical reason to think, ever have exactly similar sensations 
related to the same physical object at the same moment ; 
on the other hand, even the most private sensation has 
'correlations which would theoretically enable another 
observer to infer it. 

That no sensation is ever completely public, results 
from differences of point of view. Two people looking 
at the same table do not get the same sensation, because 
of perspective and the way the light falls. They get 
only correlated sensations. Two people listening to the 
same sound do not hear exactly the same thing, because 
one is nearer to the source of the sound than the other, 
one has better hearing than the other, and so on. Thus 
publicity in sensations consists, not in having precisely 
similar sensations, but in having more or less similar 
sensations correlated according to ascertainable laws. 
The sensations which strike us as public are those where 
the correlated sensations are very similar and the correla- 
tions are very easy to discover. But even the most 
private sensations have correlations with things that 
others can observe. The denti'st does not observe your 
ache, but he can see the cavity which causes it, and could 
guess that you are suffering even if you did not tell him. 
This fact, however, cannot be used, as Watson would 
apparently wish, to extrude from science observations 
which are private to one observer, since it is by means 
of many such observations that correlations are established, 
e.g. between toothaches and cavities. Privacy, therefore 
does not by itself make a datum unamenable to scientific 
treatment. On this point, the argument against intro- 
spection must be rejected. 


(2) Does everything observable obey the laws of physics ? 
We come now to the second ground of objection to intro- 
spection, namely, that its data do not obey the laws of 
physics. This, though less emphasized, is, I think, an 
objection which is really more strongly felt than the 
objection of privacy. And we obtain a definition of intro- 
spection more in harmony with usage if we define it as obser- 
vation of data not subject to physical laws than if we define 
it by means of privacy. No one would regard a man as 
introspective because he was conscious of having a stomach- 
ache. Opponents of introspection do not mean to deny 
the obvious fact that we can observe bodily sensations 
which" others cannot observe. For example, Knight 
Dunlap contends that images are really muscular con- 
tractions, 1 and evidently regards our awareness of muscular 
contractions as not coming under the head of introspection. 
I think it will be found that the essential characteristic 
of introspective data, in the sense which now concerns 
us, has to do with localization : either they are not localized 
at all, or they are localized, like visual images, in a place 
already physically occupied by something which would 
be inconsistent with them if they were regarded as part 
of the physical world. If you have a visual image of 
your friend sitting in a chair which in fact is empty, 
you cannot locate the image in your body, because it 
is visual, nor (as a physical phenomenon) in the chair, 
because the chair, as a physical object, is empty. Thus 
it seems to follow that the physical world does not include 

1 Psychological Review, 1916, " Thought-Content and Feeling/' 
p. 59. See also ib., 1912, " The Nature of Perceived Relations/' 
where he says : " ' Introspection/ divested of its mythological 
suggestion of the observing of consciousness, is really the observa- 
tion of bodily sensations (sensibles) and feelings (feelables) " 
(p. 427 .) 


all that we are aware of, and that images, which are 
introspective data, have to be regarded, for the present, 
as not obeying the laws of physics ; this is, I think, one 
of the chief reasons why an attempt is made to reject 
them. I shall try to show in Lecture VIII that the 
purely empirical reasons for accepting images are over- 
whelming. But we cannot be nearly so certain that they 
will not ultimately be brought under the laws of physics. 
Even if this should happen, however, they would still be 
distinguishable from sensations by their proximate causal 
laws, as gases remain distinguishable from solids. 

(3) Can we observe anything intrinsically different from 
sensations ? We come now to our third question con- 
cerning introspection. It is commonly thought that by 
looking within we can observe all sorts of things that are 
radically different from the constituents of the physical 
world, e.g. thoughts, beliefs, desires, pleasures, pains and 
emotions. The difference between mind and matter is 
increased partly by emphasizing these supposed introspec- 
tive data, partly by the supposition that matter is composed 
of atoms or electrons or whatever units physics may at 
the moment prefer. As against this latter supposition, 
I contend that the ultimate constituents of matter are 
not atoms or electrons, but sensations, and other things 
similar to sensations as regards extent and duration. 
As against the view that introspection reveals a mental 
world radically different from sensations, I propose to 
argue that thoughts, beliefs, desires, pleasures, pains 
and emotions are all built up out of sensations and images 
alone, and that there is reason to think that images do 
not differ from sensations in their intrinsic character. 
We thus effect a mutual rapprochement of mind and matter, 
and reduce the ultimate data of introspection (in our 


second sense) to images alone. On this third view of 
the meaning of introspection, therefore, our decision is 
wholly against it. 

There remain two points to be considered concerning 
introspection. The first is as to how far it is trustworthy ; 
the second is as to whether, even granting that it reveals 
no radically different stuff from that revealed by what 
might be called external perception, it may not reveal 
different relations, and thus acquire almost as much 
importance as is traditionally assigned to it. 

To begin with the trustworthiness of introspection. 
It is common among certain schools to regard the know- 
ledge of our own mental processes as incomparably more 
certain than our knowledge of the " external " world ; 
this view is to be found in the British philosophy which 
descends from Hume, and is present, somewhat veiled, in 
Kant and his followers. There seems no reason whatever 
to accept this view. Our spontaneous, unsophisticated 
beliefs, whether as to ourselves or as to the outer world, 
are always extremely rash and very liable to error. The 
acquisition of caution is equally necessary and equally 
difficult in both directions. Not only are we often un- 
aware of entertaining a belief or desire which exists in us ; 
we are often actually mistaken. The fallibility of intro- 
spection as regards what we desire is made evident by 
psycho-analysis ; its fallibility as to what we know is 
easily demonstrated. An autobiography, when con- 
fronted by a careful editor with documentary evidence, 
is usually found to be full of obviously inadvertent errors. 
Any of us confronted by a forgotten letter written some 
years ago will be astonished to find how much more 
foolish our opinions were than we had remembered them 
as being. And as to the analysis of our mental operations 


believing, desiring, willing, or what not introspection 
unaided gives very little help : it is necessary to construct 
hypotheses and test them by their consequences, just 
as we do in physical science. Introspection, therefore, 
though it is one among our sources of knowledge, is not, 
in isolation, in any degree more trustworthy than 
" external " perception. 

I come now to our second question : Does introspection 
give us materials for the knowledge of relations other 
than those arrived at by reflecting upon external percep- 
tion ? It might be contended that the essence of what 
is " mental " consists of relations, such as knowing for 
example, and that our knowledge concerning these 
essentially mental relations is entirely derived from 
introspection. If " knowing " were an unanalysable re- 
lation, this view would be incontrovertible, since clearly 
no such relation forms part of the subject matter of physics. 
But it would seem that " knowing " is really various 
relations, all of them complex. Therefore, until they 
have been analysed, our present question must remain 
unanswered. I shall return to it at the end of the present 
course of lectures. 


IN Lecture V we found reason to think that the ultimate 
constituents x of the world do not have the characteristics 
of either mind or matter as ordinarily understood : they 
are not solid persistent objects moving through space, 
nor are they fragments of "consciousness." But we 
found two ways of grouping particulars, one into " things " 
or " pieces of matter," the other into series of " per- 
spectives," each series being what may be called a 
" biography." Before we can define either sensations or 
images, it is necessary to consider this twofold classifi- 
cation in somewhat greater detail, and to derive from it 
a definition of perception. It should be said that, in 
so far as the classification assumes the whole world of 
physics (including its unperceived portions), it contains 
hypothetical elements. But we will not linger on the 
grounds for admitting these, which belong to the philosophy 
of physics rather than of psychology. 

The physical classification of particulars collects together 

1 When I speak of " ultimate constituents/' I do not mean 
necessarily such as are theoretically incapable of Analysis, but 
only such as, at present, we can see no means of analysing. I 
speak of such constituents as " particulars/' or as " relative par- 
ticulars " when I wish to emphasize the fact that they may be 
themselves complex. 



all those that are aspects of one " thing." Given any 
one particular, it is found often (we do not say always) 
that there are a number of other particulars differing 
from this one in gradually increasing degrees. Those (or 
some of those) that differ from it only very slightly will 
be found to differ approximately according to certain 
laws which may be called, in a generalized sense, the 
laws of " perspective " ; they include the ordinary laws 
of perspective as a special case. This approximation 
growt more and more nearly exact as the difference 
grows less ; in technical language, the laws of perspective 
account for the differences to the first order of small 
quantities, and other laws are only required to account 
for second-order differences. That is to say, as the 
difference diminishes, the part of the difference which 
is not according to the laws of perspective diminishes 
much more rapidly, and bears to the total difference a 
ratio which tends towards zero as both are made smaller 
and smaller. By this means we can theoretically collect 
together a number of particulars which may be defined 
as the " aspects " or " appearances " of one thing at 
one time. If the laws of perspective were sufficiently 
known, the connection between different aspects would 
be expressed in differential equations. 

This gives us, so far, only those particulars which 
constitute one thing at one time. This set of particulars 
may be called a " momentary thing." To define that 
series of " momentary things " that constitutes the 
successive states of one thing is a problem involving 
the laws of dynamics. These give the laws governing the 
changes of aspects from one time to a slightly later time, 
with the same sort of differential approximation to 
exactness as we obtained for spatially neighbouring 


aspects through the laws of perspective. Thus a momen- 
tary thing is a set of particulars, while a thing (which 
may be identified with the whole history of the thing) 
is a series of such sets of particulars. The particulars 
in one set are collected together by the laws of perspec- 
tive ; the successive sets are collected together by the 
laws of dynamics. This is the view of the world which 
is appropriate to traditional physics. 

The definition of a " momentary thing " involves 
problems .concerning time, since the particulars consti- 
tuting a momentary thing will not be all simultaneous, 
but will travel outward from the thing with the velocity 
of light (in case the thing is in vacuo). There are 
complications connected with relativity, but for our 
present purpose they are not vital, and I shall ignore 

Instead of first collecting together all the particulars 
constituting a momentary thing, and then forming the 
series of successive sets, we might have first collected 
together a series of successive aspects related by the 
laws of dynamics, and then have formed the set of such 
series related by the laws of perspective. To illustrate 
by the case of an actor on the stage : our first plan was 
to collect together all the aspects which he presents to 
different spectators at one time, and then to f6rm the 
series of such set. Our second plan is first to collect 
together all the aspects which he presents successively 
to a given spectator, and then to do the same thing for 
the other spectators, thus forming a set of series instead 
of a series of sets. The first plan tells us what he does ; 
the second the impressions he produces. This second 
way of classifying particulars is one which obviously 
has more relevance to psychology than the other. It is 


partly by this second method of classification that we 
obtain definitions of one " experience V or " biography " 
or " person/' This method of classification is also 
essential to the definition of sensations and images, as 
I shall endeavour to prove later on. But we must first 
amplify the definition of perspectives and biographies. 

In our illustration of the actor, we spoke, for the 
moment, as though each spectator's mind were wholly 
occupied by the one actor. If this were the case, it 
might be possible to define the biography of one spectator 
as a series of successive aspects of the actor related 
according to the laws of dynamics. But in fact this is 
not the case. We are at all times during our waking 
life receiving a variety of impressions, which are aspects 
of a variety of things. We have to consider what binds 
together two simultaneous sensations in one person, 
or, more generally, any two occurrences which form part 
of one experience. We might say, adhering to the stand- 
point of physics, that two aspects of different things 
belong to the same perspective when they are in the 
same place. But this would not really help us, since a 
" place " has not yet been defined. Can we define what 
is meant by saying that two aspects are " in the same 
place," without introducing anything beyond the laws 
of perspective and dynamics ? 

I do not feel sure whether it is possible to frame such 
a definition or not ; accordingly I shall not assume that 
it is possible, but shall seek other characteristics by which 
a perspective or biography may be defined. 

When (for example) we see one man and hear another 
speaking at the same time, what we see and what we 
hear have a relation which we can perceive, which makes 
the two together form, in some sense, one experience. 


It is when this relation exists that two occurrences become 
associated. Semon's " engram " is formed by all that 
we experience at one time. He speaks of two parts of 
this total as having the relation of " Nebeneinander " 
(M. 118 ; M.E. 33 ff.), which is reminiscent of Herbart's 
" Zusammen." I think the relation may be called 
simply " simultaneity." It might be said that at any 
moment all sorts of things that are not part of my ex- 
perience are happening in the world, and that therefore 
the relation we are seeking to define cannot be merely 
simultaneity. This, however, would be an error the 
sort of error that the theory of relativity avoids. There 
is not' one universal time, except by an elaborate con- 
struction ; there are only local times, each of which may 
be taken to be the time within one biography. Accord- 
ingly, if I am (say) hearing a sound, the only occurrences 
that are, in any simple sense, simultaneous with my sensa- 
tion are events in my private world, i.e. in my biography. 
We may therefore define the " perspective " to which 
the sensation in question belongs as the set of particulars 
that are simultaneous with this sensation. And similarly 
we may define the " biography " to which the sensation 
belongs as the set of particulars that are earlier or later 
than, or simultaneous with, the given sensation. More- 
over, the very same definitions can be applied to particu- 
lars which are not sensations. They are actually required 
for the theory of relativity, if we are to give a philosophical 
explanation of what is meant by " local time " in that 
theory. The relations of simultaneity and succession 
are known to us in our own experience ; they may be 
analysable, but that does not affect their suitability for 
defining perspectives ^and biographies. Such time-relations 
as can be constructed between events in different bio- 


graphics are of a different kind : they are not experienced, 
and are merely logical, being designed to afford con- 
venient ways of stating the correlations between different 

It is not only by time-relations that the parts of one 
biography are collected together in the case of living 
beings. In this case there are the mnemic phenomena 
which constitute the unity of one " experience," and 
transform mere occurrences into " experiences." I have 
already dwelt upon the importance of mnemic phenomena 
for psychology, and shall not enlarge upon them now, 
beyond observing that they are what transforms a bio- 
graphy (in our technical sense) into a life. It is they 
that give the continuity of a " person " or a " mind." 
But there is no reason to suppose that mnemic phenomena 
are associated with biographies except in the case of 
animals and plants. 

Our twofold classification of particulars gives rise to 
the dualism of body and biography in regard to everything 
in the universe, and not only in regard to living things. 
This arises as follows. Every particular of the sort 
considered by physics is a member of two groups : 

(1) The group of particulars constituting the other 

aspects of the same physical object ; 

(2) The group of particulars that have direct time- 

relations to the given particular. 

Each of these is associated with a place. When I look 
at a star, my sensation is : 

(i) A member of the group of particulars which is 
the star, and which is associated with the 
place where the star is ; 


(2) A member of the group of particulars which is 
my biography, and which is associated with 
the place where I am. x 

The result is that every particular of tjtie kind relevant 
to physics is associated with two places ; e.g. my sensa- 
tion of the star is associated with the place where I am 
and with the place where the star is. This dualism has 
nothing to do with any " mind " that I may be supposed 
to possess ; it exists in exactly the same sense if I am 
replaced by a photographic plate. We may call the two 
places the active and passive places respectively. 2 Thus 
in the case of a perception or photograph of a star, the 
active place is the place where the star is, while the 
passive place is the place where the percipient or photo- 
graphic plate is. 

We can thus, without departing from physics, collect 
together all the particulars actively at a given place, or 
all the particulars passively at a given place. In our 
own case, the one group is our body (or our brain), while 
the other is our mind, in so far as it consists of perceptions. 
In the case of the photographic plate, the first group is 
the plate as dealt with by physics, the second the aspect 
of the heavens which it photographs. (For the sake of 
schematic simplicity, I am ignoring various complica- 
tions connected with time, which require some tedious 
but perfectly feasible elaborations.) Thus what may be 
called subjectivity in the point of view is not a distinctive 
peculiarity of mind : it is present just as much in the 

1 I have explained elsewhere the manner in which ispace is con- 
structed on this theory, and in which the position of a perspective 
is brought into relation with the position of a physical object (Our 
Knowledge of the External World, Lecture III, pp. 90, 91), 

* I use these as mere names ; I do not want to introduce any 
notion of " activity." 


photographic plate. And the photographic plate has its 
biography as well as its "matter." Bjifc this biography 
is an affair of physics, and has none of the peculiar 
characteristics by which " mental " phenomena are dis- 
tinguished, with the sole exception of subjectivity. 

Adhering, for the moment, to the standpoint of physics, 
we may define a " perception " of an object as the appear- 
ance of the object from a place where there is a brain 
(or, in lower animals, some suitable nervous structure), 
with sense-organs and nerves forming part of the inter- 
vening medium. Such appearances of objects are dis- 
tinguished from appearances in other places by certain 
peculiarities, namely : 

(1) They give rise to mnemic phenomena ; 

(2) They are themselves affected by mnemic pheno- 


That is to say, they may be remembered and associated 
or influence our habits, or give rise to images, etc., and 
they are themselves different from what they would 
have been if our past experience had been different 
for example, the effect of a spoken sentence upon the 
hearer depends upon whether the hearer knows the 
language or not, which is a question of past experience. 
It is these two characteristics, both connected with 
mnemic phenomena, that distinguish perceptions from 
the appearances of objects in places where there is no 
living being. 

Theoretically, though often not practically, we can, in 
our perception of an object, separate the part which is 
due to past experience from the part which proceeds 
without mnemic influences out of the character of the 
object. We may define as " sensation " that part which 


proceeds in this way, while the remainder, which is a 
mnemic phenomenon, will have to be added to the sensation 
to make up what is called the " perception." According 
to this definition, the sensation is a theoretical core in 
the actual experience ; the actual experience is the 
perceptipn. It is obvious that there are grave difficulties 
in carrying out these definitions, but we will not linger 
over them. We have to pass, as soon as we can, from 
the physical standpoint, which we have been hitherto 
adopting, to the standpoint of psychology, in which we 
make more use of introspection in the first of the three 
senses discussed in the preceding lecture. 

But before making the transition, there are two points 
which must be made clear. First : Everything outside 
my own personal biography is outside my experience ; 
therefore if anything can be known by me outside my 
biography, it can only be known in one of two ways : 

(1) By inference from things within my biography, or 

(2) By some a priori principle independent of experi- 


I do not myself believe that anything approaching cer- 
tainty is to be attained by either of these methods, and 
therefore whatever lies outside my personal biography 
must be regarded, theoretically, as hypothesis. The 
theoretical argument for adopting the hypothesis is that 
it simplifies the statement of the laws according to which 
events happen in our experience. But there is no very 
good ground for supposing that a simple law is more 
likely to be true than a complicated law, though there 
is good ground for assuming a simple law in scientific 
practice, as a working hypothesis, if it explains the facts 
as well as another which is less simple. Belief in the 


existence of things outside my own biography exists 
antecedently to evidence, and can only be destroyed, 
if at all, by a long course of philosophic doubt. For 
purposes of science, it is justified practically by the 
simplification which it introduces into the laws of physics. 
But from the standpoint of theoretical logic it must be 
regarded as a prejudice, not as a well-grounded theory. 
With this proviso, I propose to continue yielding to the 

The second point concerns +he relating of our point of 
view to that which regards sensations as caused by 
stimuli external to the nervous system (or at least to the 
brain), and distinguishes images as " centrally excited," 
i.e. due to causes in the brain which cannot be traced 
back to anything affecting the sense-organs. It is clear 
that, if our analysis of physical objects has been valid, 
this way of defining sensations needs re-interpretation. 
It is also clear that we must be able to find such a new 
interpretation if our theory is to be admissible. 

To make the matter clear, we will take the simplest 
possible illustration. Consider a certain star, and suppose 
for the moment that its size is negligible. That is to 
say, we will regard it as, for practical purposes, a luminous 
point. Let us further suppose that it exists only for a 
very brief time, say a second. Then, according to physics, 
what happens is that a spherical wave of light travels 
outward from the star through space, just as, when you 
drop a stone into a stagnant pond, ripples travel outward 
ftom the place where the stone hit the water. The wave 
of light travels with a certain very nearly constant velocity, 
roughly 300,000 kilometres per second. This velocity may 
be ascertained by sending a flash of light to a mirror, 
and observing how long it takes before the reflected 


flash reaches you, just as the velocity of sound may be 
ascertained by means of an echo. 

What it is that happens when a wave of light reaches 
a given place we cannot tell, except in the sole case when 
the place in question is a brain connected with an eye 
which is turned in the right direction. In this one very 
special case we know what happens : we have the sensation 
called " seeing the star." In all other cases, though we 
know (more or less hypothetically) some of the corre- 
lations and abstract properties of the appearance of 
the star, we do not know the appearance itself. Now 
you may, for the sake of illustration, compare the different 
appearances of the star to the conjugation of a Greek 
verb, except that the number of its parts is really infinite, 
and not only apparently so to the despairing schoolboy. 
In vacuo, the parts are regular, and can be derived from 
the (imaginary) root according to the laws of grammar, 
i.e. of perspective. The star being situated in empty 
space, it may be defined, for purposes of physics, as 
consisting of all those appearances which it presents 
in vacuo, together with those which, according to the 
laws of perspective, it would present elsewhere if its 
appearances elsewhere were regular. This is merely the 
adaptation of the definition of matter which I gave in 
an earlier lecture. The appearance of a star at a certain 
place, if it is regular, does not require any cause or ex- 
planation beyond the existence of the star. Every 
regular appearance is an actual member of the system 
which is the star, and its causation is entirely internal 
to that system. We may express this by saying that 
a regular appearance is due to the star alone, and is 
actually part of the star, in the sense in which a man is 
part of the human race. 


But presently the light of the star reaches our atmo- 
sphere. It begins to be refracted, and dimmed by mist, 
and its velocity is slightly diminished. At last it reaches 
a human eye, where a complicated process takes place, 
ending in a sensation which gives us our grounds for 
believing in all that has gone before. Now, the irregular 
appearances of the star are not, strictly speaking, members 
of the system which is the star, according to our definition 
of matter. The irregular appearances, however, are not 
merely irregular : they proceed according to laws which 
can be stated in terms of the matter through which the 
light has passed on its way. The sources of an irregular 
appearance are therefore twofold : 

(1) The object which is appearing irregularly ; 

(2) The intervening medium. 

It should be observed that, while the conception of 
a regular appearance is perfectly precise, the conception 
of an irregular appearance is one capable of any degree 
of vagueness. When the distorting influence of the 
medium is sufficiently great, the resulting particular can 
no longer be regarded as an appearance of an object, 
but must be treated on its own account. This happens 
especially when the particular in question cannot be 
traced back to one object, but is a blend of two or more. 
This case is normal in perception : we see as one what 
the microscope or telescope reveals to be many different 
objects. The notion of perception is therefore not a pre- 
cise one : we perceive things more or less, but always with 
a very considerable amount of vagueness and confusion. 
In considering irregular appearances, there are certain 
very natural mistakes which must be avoided. In order 
that a particular may count as an irregular appearance 


of a certain object, it is not necessary that it should 
bear any resemblance to the regular appearances as regard 
its intrinsic qualities. All that is necessary is that it 
should be derivable from the regular appearances by the 
laws which express the distorting influence of the medium. 
When it is so derivable, the particular in question may 
be regarded as caused by the regular appearances, and 
therefore by the object itself, together with the modifi- 
cations resulting from the medium. In other cases, the 
particular in question may, in the same sense, be regarded 
as caused by several objects together with the medium ; 
in this case, it may be called a confused appearance of 
several objects. If it happens to be in a brain, it may 
be called a confused perception of these objects. All 
actual perception is confused to a greater or less extent. 
We can now interpret in terms of our theory the dis- 
tinction between those mental occurrences which are 
said to have an external stimulus, and those which are 
said to be " centrally excited," i.e. to have no stimulus 
external to the brain. When a mental occurrence can 
be regarded as an appearance of an object external to 
the brain, however irregular, or even as a confused appear- 
ance of several such objects, then we may regard it as 
having for its stimulus the object or objects in question, 
or their appearances at the sense-organ concerned. When, 
on the other hand, a mental occurrence has not sufficient 
connection with objects external to the brain to be regarded 
as an appearance of such objects, then its physical causation 
(if any) will have to be sought in the brain. In the former 
case it can be called a perception ; in the latter it cannot 
be so called. But the distinction is one of degree, not 
of kind. Until this is realized, no satisfactory theory 
of perception, sensation, or imagination is possible. 


THE dualism of mind and matter, if we have been right 
so far, cannot be allowed as metaphysically valid. Never- 
theless, we seem to find a certain dualism, perhaps not 
ultimate, within the world as we observe it. The dualism 
is not primarily as to the stuff of the world, but as to 
causal laws. On this subject we may again quote 
William James. He points out that when, as we say, 
we merely " imagine " things, there are no such effects 
as would ensue if the things were what we call " real." 
He takes the case of imagining a fire : 

" I make for myself an experience of blazing fire ; I 
place it near my body ; but it does not warm me in the 
least. I lay a stick upon it and the stick either burns 
or remains green, as I please. I call up water, and pour 
it on the fire, and absolutely no difference ensues. I 
account for all such facts by calling this whole train of 
experiences unreal, a mental train. Mental t fire is what 
won't burn real sticks ; mental water is what won't 
necessarily (though of course it may) put out even a 
mental fire. . . . With ' real ' objects, on the contrary, 
consequences always accrue ; and thus the real experiences 
get sifted from the mental ones, the things from our 
thoughts of them, fanciful or true, and precipitated 



together as the stable part of the whole experience-chaos, 
under the name of the physical world. " x 

In this passage James speaks, by mere inadvertence, 
as though the phenomena which he is describing as 
" mental " had no effects. This is, of course, not the 
case : they have their effects, just as much as physical 
phenomena do, but their effects follow different laws. 
For example, dreams, as Freud has shown, are just as 
much subject to laws as are the motions of the planets. 
But the laws are different : in a dream you may be 
transported from one place to another in a moment, 
or one person may turn into another under your eyes. 
Such " differences compel you to distinguish the world 
of dreams from the physical world. - 

If the two sorts of causal laws could be sharply distin- 
guished, we could call an occurrence " physical " when 
it obeys causal laws appropriate to the physical world, 
and " mental " when it obeys causal laws appropriate 
to the mental world. Since the mental world and the 
physical world interact, there would be a boundary 
between the two : there would be events which would 
have physical causes and mental effects, while there 
would be others which would have mental causes and 
physical effects. Those that have physical causes and 
mental effects we should define as " sensations." Those 
that have mental causes and physical effects might 
perhaps be identified with what we call voluntary move- 
ments ; but they do not concern us at present. 

These definitions would have all the precision that 

could be desired if the distinction between physical and 

psychological causation were clear and sharp. As a 

matter of fact, however, this distinction is, as yet, by 

Essays in Radical Empiricism, pp. 32-3. 


no means sharp. It is possible that, with fuller knowledge, 
it will be found to be no more ultimate than the distinction 
between the laws of gases and the laws of rigid bodies. 
It also suffers from the fact that an event may be an 
effect of several causes according to several causal laws : 
we cannot, in general, point to anything unique as the 
cause of such-and-such an event. And finally it is by 
no means certain that the peculiar causal laws which 
govern mental events are not really physiological. The 
law of habit, which is one of the most distinctive, may be 
fully explicable in terms of the peculiarities of nervous 
tissue, and these peculiarities, in turn, may be explicable 
by the laws of physics. It seems, therefore, that we 
are driven to a different kind of definition. It is for 
this reason that it was necessary to develop the definition 
of perception. With this definition, we can define a 
sensation as the non-mnemic elements in a perception. 
When, following our definition, we try to decide what 
elements in our experience are of the nature of sensations, 
we find more difficulty than might have been expected. 
Prima facie, everything is sensation that comes to us 
through the senses : the sights we see, the sounds we 
hear, the smells we smell, and so on ; also such things 
as headache or the feeling of muscular strain. But in 
actual fact so much interpretation, so much of habitual 
correlation, is mixed with all such experiences, that the 
core of pure sensation is only to be extracted by careful 
investigation. To take a simple illustration : if you go 
to the theatre in your own country, you seem to hear 
equally well in the stalls or the dress circle ; in either 
case you think you miss nothing. But if you go in a 
foreign country where you have a fair knowledge of the 
language, you will seem to have grown partially deaf, 


and you will find it necessary to be much nearer the stage 
than you would need to be in your own country. The 
reason is that, in hearing our own language spoken, we 
quickly and unconsciously fill out what we really hear 
with inferences to what the man must be saying, and 
we never realize that we have not heard the words we 
have merely inferred. In a foreign language, these in- 
ferences are more difficult, and we are more dependent 
upon actual sensation. If we found ourselves in a 
foreign world, where tables looked like cushions and 
cushions like tables, we should similarly discover how 
much of what we think we see is really inference. Every 
fairly* familiar sensation is to us a sign of the things 
that usually go with it, and many of these things will 
seem to form part of the sensation. I remember in the 
early days of motor-cars being with a friend when a tyre 
burst with a loud report. He thought it was a pistol, 
and supported his opinion by maintaining that he had 
seen the flash. But of course there had been no flash. 
Nowadays no one sees a flash when a tyre bursts. 

In order, therefore, to arrive at what really is sensation 
in an occurrence which, at first sight, seems to contain 
nothing else, we have to pare away all that is due to 
habit or expectation or interpretation. This is a matter 
for the psychologist, and by no means an easy matter. 
For our purposes, it is not important to determine what 
exactly is the sensational core in any case ; it is only 
important to notice that there certainly is a sensational 
core, since habit, expectation and interpretation are 
diversely aroused on diverse occasions, and the diversity 
is clearly due to differences in what is presented to the 
senses. * When you open your newspaper in the morning, 
the actual sensations of seeing the print form a very 


minute part of what goes on in you, but they are the 
starting-point of all the rest, and it is through them that 
the newspaper is a means of information or mis-information. 
Thus, although it may be difficult to determine what 
exactly is sensation in any given experience, it is clear 
that there is sensation, unless, like Leibniz, we deny all 
action of the outer world upon us. 

Sensations are obviously the source of our knowledge 
of the world, including .our own body. It might seem 
natural to regard a sensation as itself a cognition, and 
until lately I did so regard it. When, say, I see a person 
I know coming towards me in the street, it seems as 
though the mere seeing were knowledge. It is of course 
undeniable that knowledge comes through the seeing, 
but I think it is a mistake to regard the mere seeing itself 
as knowledge. If we are so to regard it, we must dis- 
tinguish the seeing from what is seen : we must say that, 
when we see a patch of colour of a certain shape, the 
patch of colour is one thing and our seeing of it is another. 
This view, however, demands the admission of the subject, 
or act, in the sense discussed in our first lecture. If there 
is a subject, it can have a relation to the patch of colour, 
namely, the sort of relation which we might call awareness. 
In that case the sensation, as a mental event, will consist 
of awareness of the colour, while the colour itself will 
remain wholly physical, and may be called the sense- 
datum, to distinguish it from the sensation. The subject, 
however, appears to be a logical fiction, like mathe- 
matical points and instants. It is introduced, not because 
observation reveals it, but because it is linguistically 
convenient and apparently demanded by grammar. 
Nominal entities of this sort may or may not exist, 
but there is no good ground for assuming that they do. 


The functions that they appear to perform can always 
be performed by classes or series or other logical con- 
structions, consisting of less dubious entities. If we are 
to avoid a perfectly gratuitous assumption, we must 
dispense with the subject as one of the actual ingredients 
of the world. But when we do this, the possibility 
of distinguishing the sensation from the sense-datum 
vanishes ; at least I see no way of preserving the dis- 
tinction. Accordingly the sensation that we have when 
we see a patch of colour simply is that patch of colour, 
an actual constituent of the physical world, and part 
of what physics is concerned with. A patch of colour 
is certainly not knowledge, and therefore we cannot 
say that pure sensation is cognitive. Through its psy- 
chological effects, it is the cause of cognitions, partly 
by being itself a sign of things that are correlated with 
it, as e.g. sensations of sight and touch are correlated, 
and partly by giving rise to images and memories after 
the sensation is faded. But in itself the pure sensation 
is not cognitive. 

In the first lecture we considered the view of Brentano, 
that " we may define psychical phenomena by saying 
that they are phenomena which intentionally contain 
an object." We saw reasons to reject this view in general ; 
we are now concerned to show that it must be rejected 
in the particular case of sensations. The kind of argument 
which formerly made me accept Brentano's view in this 
case was exceedingly simple. When I see a patch of 
colour, it seemed to me that the colour is not psychical, 
but physical, while my seeing is not physical, but psychical. 
Hence I concluded that the colour is something other 
than my seeing of the colour. This argument, to me 
historically, was directed against idealism : the emphatic 


part of it was the assertion that the colour is physical, 
not psychical. I shall not trouble you now with the 
grounds for holding as against Berkeley that the patch 
of colour is physical ; I have set them forth before, and 
I see no reason to modify them. But it does not follow 
tliat the patch of colour is not also psychical, unless 
we assume that the physical and the psychical cannot 
overlap, which I no longer consider a valid assumption. 
If we admit as I think we should that the patch of 
colour may be both physical and psychical, the reason 
for distinguishing the sense-datum from the sensation 
disappears, and we may say that the patch of colour 
and our sensation in seeing it are identical. 

This is the view of William James, Professor Dewey, 
and the American realists. Perceptions, says Professor 
Dewey, are not per se cases of knowledge, but simply 
natural events with no more knowledge status than (say) 
a shower. " Let them [the realists] try the experiment 
of conceiving perceptions as pure natural events, not 
cases of awareness or apprehension, and they will be 
surprised to see how little they miss." x I think he is 
right in this, except in supposing that the realists will 
be surprised. Many of them already hold the view he 
is advocating, and others are very sympathetic to it. 
At any rate, it is the view which I shall adopt in these 

The stuff of the world, so far as we have experience 
of it, consists, on the view that I am advocating, of 
innumerable transient particulars such as occur in seeing, 
hearing, etc., together with images more or less resembling 
these, of which I shall speak shortly. If physics is true, 
there are, besides the particulars that we experience, 
Dewey, Essays in Experimental Logic, pp. 253, 262. 


others, probably equally (or almost equally) transient, 
which make up that part of the material world that does 
not come into the sort of contact with a living body that 
is required to turn it into a sensation. But this topic 
belongs to tjie philosophy of physics, and need not concern 
us in our present inquiry. 

Sensations are what is common to the mental and 
physical worlds ; they may be defined as the intersection 
of mind and matter. This is by no means a new view ; 
it is advocated, not only by the American authors I 
have mentioned, but by Mach in his Analysis of Sensa- 
tions, which was published in 1886. The essence of 
sensalion, according to the view I am advocating, is its 
independence of past experience. It is a core in our 
actual experiences, never existing in isolation except 
possibly in very young infants. It is not itself knowledge, 
but it supplies the data for our knowledge of the physical 
world, including our own bodies. 

There are some who believe that our mental life is 
built up out of sensations alone. This may be true ; but 
in any case I think the only ingredients required in addi- 
tion to sensations are images. What images are, and' htfw 
they are to be defined, we have now to inquire. 

The distinction between images and sensations might 
seem at first sight by no means difficult. When we shut 
our eyes and call up pictures of familiar scenes, we usually 
have no difficulty, so long as we remain awake, in dis- 
criminating between what we are imagining and what 
is really seen. If we imagine some piece of music that 
we know, we can go through it in our mind from beginning 
to end without any discoverable tendency to suppose 
that we are really hearing it. But although such cases 
are so clear that no confusion seems possible, there are 


many others that are far more difficult, and the definition 
of images is by no means an easy problem. 

To begin with : we do not always know whether what 
we are experiencing is a sensation or an image. The 
things we see in dreams when our eyes are shut must 
count as images, yet while we are dreaming they seem 
like sensations. Hallucinations often begin as persistent 
images, and only gradually acquire that influence over 
belief that makes the patient regard them as sensations. 
When we are listening for a faint sound the striking of 
a distant clock, or a horse's hoofs on the road we 
think we hear it many times before we really do, because 
expectation brings us the image, and we mistake it for 
sensation. The distinction between images and sensations 
is, therefore, by no means always obvious to inspection. 1 

We may consider three different ways in which it has 
been sought to distinguish images from sensations, namely : 

(1) By the less degree of vividness in images ; 

(2) By our absence of belief in their " physical 

reality " ; 

(3) By the fact that their causes and effects are 

different from those of sensations. 

I believe the third of these to be the only universally 
applicable criterion. The other two are applicable in 
very many cases, but cannot be used for purposes of 
definition because they are liable to exceptions. Never- 
theless, they both deserve to be carefully considered. 

(i) Hume, who gives the names " impressions " and 
" ideas " to what may, for present purposes, be iden- 
tified with our " sensations " and " images," speaks of 

1 On the distinction between images and sensations, cf. Semon, 
Die mnemiscken Empfindungen, pp. 19 20. 



impressions as " those perceptions which enter with 
most force and violence " while he defines ideas as " the 
faint images of these [i.e. of impressions] in thinking 
and reasoning ". His immediately following observa- 
tions, however, show the inadequacy of his criteria of 
" force " and " faintness." He says : 

" I believe it wilf not be very necessary to employ 
many words in explaining this distinction. Every one 
of himself will readily perceive the difference betwixt 
feeling and thinking. The common degrees of these 
are easily distinguished, though it is not impossible but 
in particular instances they may very nearly approach 
to each other. Thus in sleep, in a fever, in madness, 
or in any very violent emotions of soul, our ideas may 
approach to our impressions ; as, on the other hand, it 
sometimes happens, that our impressions are so faint 
and low that we cannot distinguish them from our ideas. 
But notwithstanding this near resemblance in a few 
instances, they are in general so very different, that no 
one can make a scruple to rank them under distinct 
heads, and assign to each a peculiar name to mark 
the difference " (Treatise of Human Nature, Part I, 
Section i). 

I think Hume is right in holding that they should 
be ranked under distinct heads, with a peculiar name for 
each. But by his own confession in the above passage, 
his criterion for distinguishing them is not always adequate. 
A definition is not sound if it only applies in cases where 
the difference is glaring : the essential purpose of a 
definition is to provide a mark which is applicable even 
in marginal ca9es except, of course, when we are dealing 
with a conception, like, e.g. baldness, which is one of 
degree and has no sharp boundaries. But so far we 


have seen no reason to think that the difference between 
sensations and images is only one of degree. 

Professor Stout, in his Manual of Psychology, after 
discussing various ways of distinguishing sensations and 
images, arrives at a view which is a modification of 
Hume's. He says (I quote from the second edition) : 

" Our conclusion is that at bottom the distinction 
between image and percept, as respectively faint and 
vivid states, is based on a difference of quality. The 
percept has an aggressiveness which does not belong to 
the image. It strikes the mind with varying degrees 
of force or liveliness according to the varying intensity 
of the stimulus. This degree of force or liveliness is 
part of what we ordinarily mean by the intensity of a 
sensation. But this constituent of the intensity of 
sensations is absent in mental imagery " (p. 419). 

This view allows for the fact that sensations may 
reach any degree of faintness e.g. in the case of a just 
visible star or a just audible sound without becoming 
images, and that therefore mere faintness cannot be the 
characteristic mark of images. After explaining the 
sudden shock of a flash of lightning or a steam-whistle, 
Stout says that " no mere image ever does strike the mind 
in this manner " (p. 417). But I believe that this criterion 
fails in very much the same instances as those in which 
Hume's criterion fails in its original form. Macbeth 

speaks of 

that suggestion 

Whose horrid image doth unfix my hair 
And make my seated heart knock at my ribs 
Against the use of nature. 

The whistle of a steam-engine could hardly have a 
stronger effect than this. A very intense emotion will 


often bring with it especially where some future action 
or some undecided issue is involved powerful compelling 
images which may determine the whole course of life, 
sweeping aside all contrary solicitations to the will by 
their capacity for exclusively possessing the mind. And 
in all cases where images, originally recognized as such, 
gradually pass into hallucinations, there must be just 
that " force or liveliness " which is supposed to be always 
absent from images. The cases of dreams and fever- 
delirium are as hard to adjust to Professor Stout's modified 
criterion as to Hume's. I conclude therefore that the 
test oi liveliness, however applicable in ordinary instances, 
cannot be used to define the differences between sensations 
and images. 

(2) We might attempt to distinguish images from 
sensations by our absence of belief in the " physical 
reality " of images. When we are aware that what 
we are experiencing is an image, we do not give it the 
kind of belief that we should give to a sensation : we 
do not think that it has the same power of producing 
knowledge of the " external world/' Images are " im- 
aginary " ; in some sense they are " unreal." But this 
difference is hard to analyse or state correctly. What 
we call the " unreality " of images requires interpretation : 
it cannot mean what would be expressed by saying " there's 
no such thing." Images are just as truly part of the 
actual world as sensations are. All that we really mean 
by calling an image " unreal " is that it does not have 
the concomitants which it would have if it were a sensa- 
tion. When we call up a visual image of -a chair, we 
do not attempt to sit in it, because we know that, like 
Macbeth's dagger, it is not " sensible to feeling as to 
sight " i.e. it does not have the correlations with tactile 


sensations which it would have if it were a visual sensation 
and not merely a visual image. But this means that 
the so-called " unreality " of images consists merely in 
their not obeying the laws of physics, and thus brings 
us back to the causal distinction between images and 

This view is confirmed by the fact that we only feel 
images to be " unreal " when we already know them to 
be images. Images cannot be defined by the feeling of 
unreality, because when we falsely believe an image to 
be a sensation, as in the case of dreams, it feels just as 
real as if it were a sensation. Our feeling of unreality 
results from our having already realized that we are 
dealing with an image, and cannot therefore be the 
definition of what we mean by an image. As soon as 
an image begins to deceive us as to its status, it also 
deceives us as to its correlations, which are what we 
mean by its " reality. 1 ' 

(3) This brings us to the third mode of distinguishing 
images from sensations, namely, by their causes and 
effects. I believe this to be the only valid ground of 
distinction. James, in the passage about the mental 
fire which won't burn real sticks, distinguishes images 
by their effects, but I think the more reliable distinction 
is by their causes. Professor Stout (loc. cit., p. 127) says : 
" One characteristic mark of what we agree in calling 
sensation is its mode of production. It is caused by 
what we call a stimulus. A stimulus is always some 
condition external to the nervous system itself and 
operating upon it." I think that this is the correct view, 
and that the distinction between images and sensations 
can only be made by taking account of their causation. 
Sensations come through sense-organs, while images do 


not. We cannot have visual sensations in the dark, 
or with our eyes shut, but we can very well have visual 
images under these circumstances. Accordingly images 
have been defined as " centrally excited sensations," 
i.e. sensations which have their physiological cause in 
the brain only, not also in the sense-organs and the 
nerves that run from the sense-organs to the brain. I 
think the phrase " centrally excited sensations " assumes 
more than is necessary, since it takes it for granted that 
an image must have a proximate physiological cause. 
This is probably true, but it is an hypothesis, and for our 
purposes an unnecessary one. It would seem to fit 
better with what we can immediately observe if we were 
to say that an image is occasioned, through association, 
by a sensation or another image, in other words that 
it has a mnemic cause which does not prevent it from 
also having a physical cause. And I think it will be 
found that the causation of an image always proceeds 
according to mnemic laws, i.e. that it is governed by 
habit and past experience. If you listen to a man playing 
the pianola without looking at him, you will have images 
of his hands on the keys as if he were playing the piano ; 
if you suddenly look at him while you are absorbed in 
the music, you will experience a shock of surprise when 
you notice that his hands are not touching the notes. 
Your image of his hands is due to the many times that 
you have heard similar sounds and at the same time seen 
the player's hands on the piano. When habit and past 
experience play this part, we are in the region of mnemic 
as opposed to ordinary physical causation. And I think 
that, if we could regard as ultimately valid the difference 
between physical and mnemic causation, we could dis- 
tinguish images from sensations as having mnemic causes, 


though they may also have physical causes. Sensations, 
on the other hand, will only have physical causes. 

However this may be, the practically effective dis- 
tinction between sensations and images is that in the 
causation of sensations, but not of images, the stimulation 
of nerves carrying an effect into the brain, usually from 
the surface of the body, plays an essential part. And 
this accounts for the fact that images and sensations 
cannot always be distinguished by their intrinsic nature. 

Images also differ from sensations as regards their 
effects. Sensations, as a rule, have both physical and 
mental effects. As you watch the train you meant to 
catch leaving the station, there are both the successive 
positions of the train (physical effects) and the successive 
waves of fury and disappointment (mental effects). 
Images, on the contrary, though they may produce 
bodily movements, do so according to mnemic laws, 
not according to the laws of physics. All their effects, 
of whatever nature, follow mnemic laws. But this differ- 
ence is less suitable for definition than the difference 
as to causes. 

Professor Watson, as a logical carrying-out of his 
behaviourist theory, denies altogether that there are 
any observable phenomena such as images are supposed 
to be. He replaces them all by faint sensations, and 
especially by pronunciation of words sotto voce. When 
we " think " of a table (say), as opposed to seeing it, 
what happens, according to him, is usually that we are 
making small movements of the throat and tongue such 
as would lead to our uttering the word " table " if they 
were more pronounced. I shall consider his view again 
in connection with words ; for the present I am only 
concerned to combat his denial of images. This denial 


is set forth both in his book on Behavior and in an 
article called " Image and Affection in Behavior " in 
the Journal of Philosophy, Psychology and Scientific 
Methods, vol. x (July, 1913). It seems to me that in 
this matter he has been betrayed into denying plain 
facts in the interests of a theory, namely, the supposed 
impossibility of introspection. I dealt with the theory 
in Lecture VI ; for the present I wish to reinforce the 
view that the facts are undeniable. 

Images are of various sorts, according to the nature 
of the sensations which they copy. Images of bodily 
movements, such as we have when we imagine moving 
an arm or, on a smaller scale, pronouncing a word, might 
possibly be explained away on Professor Watson's lines, 
as really consisting in small incipient movements such 
as, if magnified and prolonged, would be the movements 
we are said to be imagining. Whether this is the case 
or not might even be decided experimentally. If there 
were a delicate instrument for recording small movements 
in the mouth and throat, we might place such an instru- 
ment in a person's mouth and then tell him to recite a 
poem to himself, as far as possible only in imagination. 
I should not be at all surprised if it were found that actual 
small movements take place while he is " mentally " 
saying over the verses. The point is important, because 
what is called " thought " consists mainly (though I 
think not wholly) of inner speech. If Professor Watson 
is right as regards inner speech, this whole region is trans- 
ferred from imagination to sensation. But since the 
question is capable of experimental decision, it would 
be gratuitous rashness to offer an opinion while that 
decision is lacking. 

But visual and auditory images are much more diffi- 


cult to deal with in this way, because they lack the con- 
nection with physical events in the outer world which 
belongs to visual and auditory sensations. Suppose, for 
example, that I am sitting in my room, in which there 
is an empty arm-chair. I shut my eyes, and call up a 
visual image of a friend sitting in the arm-chair. If I 
thrust my image into the world of physics, it contradicts 
all the usual physical laws. My friend reached the chair 
without coming in at the door in the usual way ; sub- 
sequent inquiry will show that he was somewhere else 
at the moment. If regarded as a sensation, my image 
has all the marks of the supernatural. My image, 
therefore, is regarded as an event in me, not as having 
that position in the orderly happenings of the public 
world that belongs to sensations. By saying that it 
is an event in me, we leave it possible that it may be 
physiologically caused : its privacy may be only due 
to its connection with my body. But in any case it is 
not a public event, like an actual person walking in at 
the door and sitting down in my chair. And it cannot, 
like inner speech, be regarded as a small sensation, since 
it occupies just as large an area in my visual field as 
the actual sensation would do. 

Professor Watson says : "I should throw out imagery 
altogether and attempt to 'show that all natural 
thought goes on in terms of sensori-motor processes in 
the larynx." This view seems to me flatly to con- 
tradict experience. If you try to persuade any un- 
educated person that she cannot call up a visual picture 
of a friend sitting in a chair, but can only use words 
describing what such an occurrence would be like, she 
will conclude that you are mad. (This statement is 
based upon experiment.) Gait on, as every one knows, 


investigated visual imagery, and found that education 
tends to kill it : the Fellows of the Royal Society turned 
out to have much less of it than their wives. I see no 
reason to doubt his conclusion that the habit of abstract 
pursuits makes learned men much inferior to the average 
in power of visualizing, and much more exclusively 
occupied with words in their " thinking/' And Pro- 
fessor Watson is a very learned man. 

I shall henceforth assume that the existence of images 
is admitted, and that they are to be distinguished from 
sensations by their causes, as well as, in a lesser degree, 
by their effects. In their intrinsic nature, though they 
often differ from sensations by being more dim or vague 
or faint, yet they do not always or universally differ 
from sensations in any way that can be used for defining 
them. Their privacy need form no bar to the scientific 
study of them, any more than the privacy of bodily 
sensations does. Bodily sensations are admitted by even 
the most severe critics of introspection, although, like 
images, they can only be observed by one observer. It 
must be admitted, however, that the laws of the appear- 
ance and disappearance of images are little known and 
difficult to discover, because we are not assisted, as in 
the case of sensations, by our knowledge of the physical 

There remains one very important point concerning 
images, which will occupy us much hereafter, and that 
is, their resemblance to previous sensations. They are 
said to be " copies " of sensations, always as regards 
the simple qualities that enter into them, though not 
always as regards the manner in which these are put 
together. It is generally believed that we cannot imagine 
a shade of colour that we have never seen, or a sound 


that we have never heard. On this subject Hume is 
the classic. He says, in the definitions already quoted : 

" Those perceptions, which enter with most force and 
violence, we may name impressions ; and under this name I 
comprehend all our sensations, passions and emotions, as 
they make their first appearance in the soul. By ideas I 
mean the faint images of these in thinking and reasoning." 

He next explains the difference between simple and 
complex ideas, and explains that a complex idea may 
occur without any similar complex impression. But 
as regards simple ideas, he states that " every simple 
idea has a simple impression, which resembles it, and 
every simple impression a correspondent idea." He goes 
on to enunciate the general principle " that all our simple 
ideas in their first appearance are derived from simple 
impressions, which are correspondent to them, and which 
they exactly represent " (Treatise of Human Nature, 
Part I, Section i). 

It is this fact, that images resemble antecedent sensa- 
tions, which enables us to call them images " of " this 
or that. For the understanding of memory, and of 
knowledge generally, the recognizable resemblance of 
images and sensations is of fundamental importance. 

There are difficulties in establishing Hume's principles, 
and doubts as to whether it is exactly true. Indeed, he 
himself signalized an exception immediately after stating 
his maxim. Nevertheless, it is impossible to doubt that 
in the main simple images are copies of similar simple 
sensations which have occurred earlier, and that the 
same is true of complex images in all cases of memory 
as opposed to mere imagination. Our power of acting 
with reference to what is sensibly absent is largely due 
to this characteristic of images, although, as education 


advances, images tend to be more and more replaced 
by words. We shall have much to say in the next two 
lectures on the subject of images as copies of sensations. 
What has been said now is merely by way of reminder 
that this is their most notable characteristic. 

I am by no means confident that the distinction 
between images and sensations is ultimately valid, and I 
should be glad to be convinced that images can be 
reduced to sensations of a peculiar kind. I think it is 
clear, however, that, at any rate in the case of auditory 
and visual images, they do differ from ordinary auditory 
and visual sensations, and therefore form a recognizable 
class of occurrences, even if it should prove that they can 
be regarded as a sub-class of sensations. This is all that 
is necessary to validate the use of images to be made 
in the sequel. 


MEMORY, which we are to consider to-day, introduces 
us to knowledge in one of its forms. Tj^e analysis of 
knowledge will occupy us until the end of the thirteenth 
lecture, and is the most difficult part of our whole enter- 

I do not myself believe that the analysis of knowledge 
can be effected entirely by means of purely external 
observation, such as behaviourists employ. I shall discuss 
this question in later lectures. In the present lecture 
I shall attempt the analysis of memory-knowledge, both 
as an introduction to the problem of knowledge in general, 
and because memory, in some form, is presupposed in 
almost all other knowledge. Sensation, we decided, is 
not a form of knowledge. It might, however, have been 
expected that we should begin our discussion of knowledge 
with perception, i.e. with that integral experience of 
things in the environment, out of which sensation is 
extracted by psychological analysis. What is called 
perception differs from sensation by the fact that the 
sensational ingredients bring up habitual associates 
images and expectations of their usual correlates all of 
which are subjectively indistinguishable from the sensa- 
tion. The fact of past experience is essential in producing 


this filling-out of sensation, but not the recollection of 
past experience. The non-sensational elements in per- 
ception can be wholly explained as the result of habit, 
produced by frequent correlations. Perception, according 
to our definition in Lecture VII, is no more a form of 
knowledge than sensation is, except in so far as it involves 
expectations. The purely psychological problems which it 
raises are not very difficult, though they have sometimes 
been rendered artificially obscure by unwillingness to 
admit the fallibility of the non-sensational elements of 
perception. On the other hand, memory raises many 
difficult and very important problems, which it is necessary 
to consider at the first possible moment. 

One reason for treating memory at this early stage is 
that it seems to be involved in the fact that images are 
recognized as " copies " of past sensible experience. In 
the preceding lecture I alluded to Hume's principle 
" that all our simple ideas in their first appearance are 
derived from simple impressions, which are correspondent 
to them, and which they exactly represent." Whether 
or not this principle is liable to exceptions, everyone 
would agree that is has a broad measure of truth, though 
the word " exactly " might seem an overstatement, and 
it might seem more correct to say that ideas approximately 
represent impressions. Such modifications of Hume's 
principle, however, do not affect the problem which I 
wish to present for your consideration, namely : Why 
do we believe that images are, sometimes or always, 
approximately or exactly, copies of sensations ? What 
sort of evidence is there ? And what sort of evidence is 
logically possible ? The difficulty of this question arises 
through the fact that the sensation which an image is 
supposed to copy is in the past when the image exists, 


and can therefore only be known by memory, while, on 
the other hand, memory of past sensations seems only 
possible by means of present images. How, then, are we 
to find any way of comparing the present image and the 
past sensation ? The problem is just as acute if we say 
that images differ from their prototypes as if we say 
that they resemble them ; it is the very possibility of 
comparison that is hard to understand. 1 We think we 
can know -that they are alike or different, but we cannot 
bring them together in one experience and compare them. 
To deal with this problem, we must have a theory of 
memory. In this way the whole status of images as 
" copies " is bound up with the analysis of memory. 

In investigating memory-beliefs, there are certain 
points which must be borne in mind. In the first place, 
everything constituting a memory-belief is happening 
now, not in that past time to which the belief is said to 
refer. It is not logically necessary to the existence of a 
memory-belief that the event remembered should have 
occurred, or even that the past should have existed at all. 
There is no logical impossibility in the hypothesis that 
the world sprang into being five minutes ago, exactly 
as it then was, with a population that " remembered " a 
wholly unreal past. There is no logically necessary 
connection between events at different times ; therefore 
nothing that is happening now or will happen in the 
future can disprove the hypothesis that the world began 

1 How, for example, can we obtain such knowledge as the 
following : " If we look at, say, a red nose and perceive it, and 
after a little while ekphore its memory-image, we note immediately 
how unlike, in its likeness, this memory-image is to the original 
perception " (A. Wohlgemuth, " On the Feelings and their Neural 
Correlate with an Examination of the Nature of Pain/' Journal 
of Psychology, vol. viii, part iv, June, 1917)- 


five minutes ago. Hence the occurrences which are called 
knowledge of the past are logically independent of the 
past ; they are wholly analysable into present contents, 
which might, theoretically, be just what they are even if 
no past had existed. 

I am not suggesting that the non-existence of the past 
should be entertained as a serious hypothesis. Like all 
sceptical hypotheses, it is logically tenable, but unin- 
teresting. All that I am doing is to use its logical 
tenability as a help in the analysis of what occurs when 
we remember. 

In the second place, images without beliefs are in- 
sufficient to constitute memory ; and habits are still 
more insufficient. The behaviourist, who attempts to 
make psychology a record of behaviour, has to trust his 
memory in making the record. " Habit " is a concept 
involving the occurrence of similar events at different 
iimes ; if the behaviourist feels confident that there is 
such a phenomenon as habit, that can only be because 
he trusts his memory, when it assures him that there have 
been other times. And the same applies to images. If 
we are to know as it is supposed we do that images 
are " copies," accurate or inaccurate, of past events, 
something more than the mere occurrence of images must 
go to constitute this knowledge. For their mere occur- 
rence, by itself, would not suggest any connection with 
anything that had happened before. 

Can we constitute memory out of images together with 
suitable beliefs ? We may take it that memory-images, 
when they occur in tnie memory, are (a) known to be 
copies, (b) sometimes known to be imperfect copies 
(cf. footnote on previous page). How is it possible to 
know that a memory-image is an imperfect copy, without 


having a more accurate copy by which to replace it ? 
This would seem to suggest that we have a way of knowing 
the past which is independent of images, by means of 
which we can criticize image-memories. But I do not 
think such an inference is warranted. 

What results, formally, from our knowledge of the 
past through images of which we recognize the inaccuracy, 
is that such images must have two characteristics by 
which we can arrange them in two series, of which one 
corresponds to the more or less remote period in the past 
to which they refer, and the other to our greater or less 
confidence in their accuracy. We will take the second 
of these points first. 

Our confidence or lack of confidence in the accuracy 
of a memory-image must, in fundamental cases, be based 
upon a characteristic of the image itself, since we cannot 
evoke the past bodily and compare it with the present 
image. It might be suggested that vagueness is the 
required characteristic, but I do not think this is the 
case. We sometimes have images that are by no means 
peculiarly vague, which yet we do not trust for example, 
under the influence of fatigue we may see a fri nd's face 
vividly and clearly, but horribly distorted. In such a 
case we distrust our image in spite of its being unusually 
clear. I think the characteristic by which we distin- 
guish the images we trust is the feeling of familiarity that 
accompanies them. Some images, like some sensations, 
feel very familiar, while others feel strange. Familiarity 
is a feeling capable of degrees. In an image of a well- 
known face, for example, some parts may feel more 
familiar than others ; when this happens, we have more 
belief in the accuracy of the familiar parts than in that 
of the unfamiliar parts. I think it is by this means that 



we become critical of images, not by some imageless 
memory with which we compare them. I shall return to 
the consideration of familiarity shortly. 

I come now to the other characteristic which memory- 
images must have, in order to account for our knowledge 
of the past. They must have some characteristic which 
makes us regard them as referring to more or less remote 
portions of the past. That is to say, if we suppose that 
A is the event remembered, B the remembering, and t 
the interval of time between A and B, there must be 
some characteristic of B which is capable of degrees, and 
which, in accurately dated memories, varies as t varies. It 
may increase as t increases, or diminish as t increases. The 
question which of these occurs is not of any importance for 
the theoretic serviceability of the characteristic in question. 

In actual fact, there are doubtless various factors that 
concur in giving us the feeling of greater or less remote- 
ness in some remembered event. There may be a specific 
feeling which could be called the feeling of " pastness," 
especially where immediate memory is concerned. But 
apart from this, there are other marks. One of these is 
context. A recent memory has, usually, more context than 
a more distant one. When a remembered event has a 
remembered context, this may occur in two ways, either 
(a) by successive images in the same order as their proto- 
types, or (b) by remembering a whole process simul- 
taneously, in the same way in which a present process 
may be apprehended, through akoluthic sensations which, 
by fading, acquire the mark of just-pastness in an increasing 
degree as they fade, and are thus placed in a series while 
all sensibly present. It will be context in this second 
sense, more specially, that will give us a sense of the 
nearness or remoteness of a remembered event. 


There is, of course, a difference between knowing the 
temporal relation of a remembered event to the present, 
and knowing the time-order of two remembered events. 
Very often our knowledge of the temporal relation of a 
remembered event to the present is inferred from its 
temporal relations to other remembered events. It would 
seem that only rather recent events can be placed at all 
accurately by means of feelings giving their temporal 
relation to the present, but it is clear that such feelings 
must play an essential part in the process of dating remem- 
bered events. 

We may say, then, that images are regarded by us as 
more or less accurate copies of past occurrences because 
they come to us with two sorts of feelings : (i) Those 
that may be called feelings of familiarity ; (2) those that 
may be collected together as feelings giving a sense of 
pastness. The first lead us to trust our memories, the 
second to assign places to them in the time-order. 

We have now to analyse the memory-belief, as opposed 
to the characteristics of images which lead us to base 
memory-beliefs upon them. 

If we had retained the " subject " or " act " in know- 
ledge, the whole problem of memory would have been 
comparatively simple. We could then have said that 
remembering is a direct relation between the present 
act or subject and the past occurrence remembered : the 
act of remembering is present, though its object is past. 
But the rejection of the subject renders some more com- 
plicated theory necessary. Remembering has to be a 
present occurrence in some way resembling, or related to, 
what is remembered. And it is difficult to find any 
ground, except a pragmatic one, for supposing that memory 
is not sheer delusion, if, as seems to be the case, there is 


not, apart from memory, any way of ascertaining that 
there really was a past occurrence having the required 
relation to our present remembering. What, if we fol- 
lowed Meinong's terminology, we should call the " object " 
in memory, i.e. the past event which we are said to be 
remembering, is unpleasantly remote from the " content/' 
i.e. the present mental occurrence in remembering. There 
is an awkward gulf between the two, which raises difficulties 
for the theory of knowledge. But we must not falsify 
observation to avoid theoretical difficulties. For the 
present, therefore, let us forget these problems, and try 
to discover what actually occurs in memory. 

Some points may be taken as fixed, and such as any 
theory of memory must arrive at. In this case, as in 
most others, what may be taken as certain in advance 
is rather vague. The study of any topic is like the con- 
tinued observation of an object which is approaching us 
along a road : what is certain to begin with is the quite 
vague knowledge that there is some object on the road. 
If you attempt to be less vague, and to assert that the 
object is an elephant, or a man, or a mad dog, you run 
a risk of error ; but the purpose of continued observation 
is to enable you to arrive at such more precise knowledge. 
In like manner, in the study of memory, the certainties 
with which you begin are very vague, and the more precise 
propositions at which you try to arrive are less certain 
than the hazy data from which you set out. Never- 
theless, in spite of the risk of error, precision is the goal 
at which we must aim. 

The first of our vague but indubitable data is that 
there is knowledge of the past. We do not yet know 
jvith any precision what we mean by " knowledge," and 
we must admit that ia any given instance our memory 


may be at fault. Nevertheless, whatever a sceptic might 
urge in theory, we cannot practically doubt that we got 
up this morning, that we did various things yesterday, 
that a great war has been taking place, and so on. How 
far our knowledge of the past is due to memory, and 
how far to -other sources, is of course a matter to be 
investigated, but there can be no doubt that memory 
forms an indispensable part of our knowledge of the past. 

The second datum is that we certainly have more capacity 
for knowing the past than for knowing the future. We 
know some things about the future, for example what 
eclipses there will be ; but this knowledge is a matter 
of elaborate calculation and inference, whereas some of 
our knowledge of the past comes to us without effort, 
in the same sort of immediate way in which we acquire 
knowledge of occurrences in our present environment. 
We might provisionally, though perhaps not quite cor- 
rectly, define " memory " as that way of knowing about 
the past which has no analogue in our knowledge of the 
future ; such a definition would at least serve to mark the 
problem with which we are concerned, though some 
expectations may deserve to rank with memory as regards 

A third point, perhaps not quite so certain as our 
previous two, is that the truth of memory cannot be wholly 
practical, as pragmatists wish all truth to be. It seems 
clear that some of the things I remember are trivial and 
without any visible importance for the future, but that 
my memory is true (or false) in virtue of a past event, 
not in virtue of any future consequences of my belief. 
The definition of truth as the correspondence between 
beliefs and facts seems peculiarly evident in the case of 
memory, as against not only the pragmatist definition 


but also the idealist definition by means of coherence. 
These considerations, however, are taking us away from 
psychology, to which we must now return. 

It is important not to confuse the two forms of memory 
which Bergson distinguishes in the second chapter of his 
Matter and Memory, namely the sort that consists of 
habit, and the sort that consists of independent recol- 
lection. He gives the instance of learning a lesson by 
heart : when I know it by heart I am said to " remembet// 
it, but this merely means that I have acquired certain 
habits ; on the other hand, my recollection of (say) the 
second time I read the lesson while I was learning it is 
the recollection of a unique event, which occurred only 
once. The recollection of a unique event cannot, so 
Bergson contends, be wholly constituted by habit, and is 
in fact something radically different from the memory 
which is habit. The recollection alone is true memory. 
This distinction is vital to the understanding of memory. 
But it is not so easy to carry out in practice as it is to 
draw in theory. Habit is a very intrusive feature of our 
mental life, and is often present where at first sight it 
seems not to be. There is, for example, a habit of remem- 
bering a unique event. When we have once described 
the event, the words we have used easily become habitual. 
We may even have used words to describe it to ourselves 
while it was happening ; in that case, the habit of these 
words may fulfil the function of Bergson's true memory, 
while in reality it is nothing but habit-memory. A 
gramophone, by the help of suitable records, might relate 
to us the incidents of its past ; and people are not so 
different from gramophones as they like to believe. 

In spite, however, of a difficulty in distinguishing the 
two forms of memory in practice, there can be no doubt 


that both forms exist. I can set to work now to remember 
things I never remembered before, such as what I had 
to eat for breakfast this morning, and it can hardly be 
wholly habit that enables me to do this. It is this sort 
of occurrence that constitutes the essence of memory. 
Until we have analysed what happens in such a case as 
this, we have not succeeded in understanding memory. 

The sort of memory with which we are here concerned 
is the sort which is a form of knowledge. Whether know- 
ledge itself is reducible to habit is a question to which 
I shall return in a later lecture ; for the present I am 
only anxious to point out that, whatever the true analysis 
of knowledge may be, knowledge of past occurrences is 
not proved by behaviour which is due to past experience. 
The fact that a man can recite a poem does not show 
that he remembers any previous occasion on which he 
has recited or read it. Similarly, the performances of 
animals in getting out of cages or mazes to which they 
are accustomed do not prove that they remember having 
been in the same situation before. Arguments in favour 
of (for example) memory in plants are only arguments 
in favour of habit-memory, not of knowledge-memory. 
Samuel Butler's arguments in favour of the view that an 
animal remembers something of the lives of its ancestors I 
are, when examined, only arguments in favour of habit- 
memory. Semon's two books, mentioned in an earlier 
lecture, do not touch knowledge-memory at all closely. 
They give laws according to which images of past occur- 
rences come into our minds, but do not discuss our belief 
that these images refer to past occurrences, which is 
what constitutes knowledge-memory. It is this that is 
of interest to theory of knowledge. I shall speak of it 
1 See his Life and Habit and Unconscious Mtmory 


as " true " memory, to distinguish it from mere habit 
acquired through past experience. 

Before considering true memory, it will be well to 
consider two things which are on the way towards memory, 
namely the feeling of familiarity and recognition. 

We often feel that something in our sensible environ- 
ment is familiar, without having any definite recollection 
of previous occasions on which we have seen it. We 
have this feeling normally in places where we have often 
been before at home, or in well-known streets. Most 
people and animals find it essential to their happiness to 
spend a good deal of their time in familiar surroundings, 
which are especially comforting when any danger threatens. 
The feeling of familiarity has all sorts of degrees, down 
to the stage where we dimly feel that we have seen a 
person before. It is by no means always reliable ; 
almost everybody has at some time experienced the 
well-known illusion that all that is happening now hap- 
pened before at some time. There are occasions when 
familiarity does not attach itself to any definite object, 
when there is merely a vague feeling that something is 
familiar. This is illustrated by Turgenev's Smoke, where 
the hero is long puzzled by a haunting sense that some- 
thing in his present is recalling something in his past, 
and at last traces it to the smell of heliotrope. Whenever 
the sense of familiarity occurs without a definite object, 
it leads us to search the environment until we are satisfied 
that we have found the appropriate object, which leads 
us to the judgment : " This is familiar." I think we 
may regard familiarity as a definite feeling, capable of 
existing without an object, but normally standing in a 
specific relation to some feature of the environment, the 
relation being that which we express in words by saying 


that the feature in question is familiar. The judgment 
that what is familiar has been experienced before is a 
product of reflection, and is no part of the feeling of 
familiarity, such as a horse may be supposed to have 
when he returns to his stable. Thus no knowledge as to 
the past is to be derived from the feeling of familiarity 

A further stage is recognition. This may be taken in 
two senses, the first when a thing not merely feels familiar, 
but we know it is such-and-such. We recognize our 
friend Jones, we know cats and dogs when we see them, 
and so on. Here we have a definite influence of past 
experience, but not necessarily any actual knowledge of 
the past. When we see a cat, we know it is a cat because 
of previous cats we have seen, but we do not, as a rule, 
recollect at the moment any particular occasion when 
we have seen a cat. Recognition in this sense does not 
necessarily involve more than a habit of association : the 
kind of object we are seeing at the moment is associated 
with the word " cat/' or with an auditory image of 
purring, or whatever other characteristic we may happen 
to recognize in the cat of the moment. We are, of course, 
in fact able to judge, when we recognize an object, that 
we have seen it before, but this judgment is something 
over and above recognition in this first sense, and may 
very probably be impossible to animals that nevertheless 
have the experience of recognition in this first sense of 
the word. 

There is, however, another sense of the word, in which 
we mean by recognition, not knowing the name of a thing 
or some other property of it, but knowing that we have 
seen it before. In this sense recognition does involve 
knowledge about the past. This knowledge is memory 


in one sense, though in another it is not. It does not 
involve a definite memory of a definite past event, but 
only the knowledge that something happening now is 
similar to something that happened before. It differs 
from the sense of familiarity by being cognitive ; it is a 
belief or judgment, which the sense of familiarity is not. 
I do not wish to undertake the analysis of belief at present, 
since it will be the subject of the twelfth lecture ; for the 
present I merely wish to emphasize the fact that recog- 
nition, in our second sense, consists in a belief, which we 
may express approximately in the words : " This has 
existed before. 1 ' 

There are, however, several points in which such an 
account of recognition is inadequate. To begin with, it 
might seem at first sight more correct to define recognition 
as " I have seen this before " than as " this has existed 
before." We recognize a thing (it may be urged) as having 
been in our experience before, whatever that may mean ; 
we do not recognize it as merely having been in the world 
before. I am not sure that there is anything substantial 
in this point. The definition of " my experience " is 
difficult ; broadly speaking, it is everything that is con- 
nected with what I am experiencing now by certain links, 
of which the various forms of memory are among the 
most important. Thus, if I recognize a thing, the occasion 
of its previous existence in virtue of which I recognize 
it forms part of " my experience " by definition : recog- 
nition will be one of the marks by which my experience is 
singled out from the rest of the world. 0^ course, the 
words " this has existed before " are a very inadequate 
translation^ of what actually happens when "we form a 
judgment of recognition, but that is unavoidable : words 
are framed to express a level of thought which is by no 


means primitive, and are quite incapable of expressing 
such an elementary occurrence as recognition. I shall 
return to what is virtually the same question in connection 
with true memory, which raises exactly similar problems. 
A second point is that, when we recognize something, 
it was not in fact the very same thing, but only something 
similar, that we experienced on a former occasion. Sup- 
pose the object in question is a friend's face. A person's 
face is always changing, and is not exactly the same on 
any two occasions. Common sense treats it as one face 
with varying expressions ; but the varying expressions 
actually exist, each at its proper time, while the one face 
is merely a logical construction. We regard two objects 
as the same, for common-sense purposes, when the reaction 
they call for is practically the same. Two visual appear- 
ances, to both of which it is appropriate to say : " Hullo, 
Jones ! " are treated as appearances of one identical 
object, namely Jones. The name " Jones " is applicable 
to both, and it is only reflection that shows us that many 
diverse particulars are collected together to form the 
meaning of the name " Jones." What we see on any 
one occasion is not the whole series of particulars that 
make up Jones, but only one of them (or a few in quick 
succession). On another occasion we see another member 
of the series, but it is sufficiently similar to count as the 
same from the standpoint of common sense. Accordingly, 
when we judge " I have seen this before/' we judge falsely 
if " this " is taken as applying to the actual constituent 
of the world that we are seeing at the moment. The 
word " this " must be interpreted vaguely so as to include 
anything sufficiently like what we are seeing at the 
moment. Here, again, we shall find a similar point as 
regards true memory ; and in connection with true memory 


we will consider the point again. It is sometimes sug- 
gested, by those who favour behaviourist views, that 
recognition consists in behaving in the same way when 
a stimulus is repeated as we behaved on the first occasion 
when it occurred. This seems to be the exact opposite 
of the truth. The essence of recognition is in the difference 
between a repeated stimulus and a new one. On the first 
occasion there is no recognition ; on the second occasion 
there is. In fact, recognition is another instance of the 
peculiarity of causal laws in psychology, namely, that the 
causal unit is not a single event, but two or more events, 
Habit is the great instance of this, but recognition is 
another. A stimulus occurring once has a certain effect ; 
occurring twice, it has the further effect of recognition. 
Thus the phenomenon of recognition has as its cause the 
two occasions when the stimulus has occurred ; either 
alone is insufficient. This complexity of causes in 
psychology might be connected with Bergson's arguments 
against repetition in the mental world. It does not prove 
that there are no causal laws in psychology, as Bergson 
suggests ; but it does prove that the causal laws of 
psychology are prima facie very different from those of 
physics. On the possibility of explaining away the 
difference as due to the peculiarities of nervous tissue I 
have spoken before, but this possibility must not be 
forgotten if we are tempted to draw unwarranted meta- 
physical deductions. 

True memory, which we must now endeavour to under- 
stand, consists of knowledge of past events, but not of 
all such knowledge. Some knowledge of past events, 
for example what we learn through reading history, is on 
a par with the knowledge we can acquire concerning the 
future : it is obtained by inference, not (so to speak) 


spontaneously. There is a similar distinction in our know- 
ledge of the present : some of it is obtained through the 
senses, some in more indirect ways. I know that there 
are at this moment a number of people ill the streets of 
New York, but I do not know this in the immediate way 
in which I know of the people whom I see by looking 
out of my window. It is not easy to state precisely 
wherein the difference between these two sorts of know- 
ledge consists, but it is easy to feel the difference. For 
the moment, I shall not stop to analyse it, but shall con- 
tent myself with saying that, in this respect, memory 
resembles the knowledge derived from the senses. It is 
immediate, not inferred, not abstract ; it differs from 
perception mainly by being referred to the past. 

In regard to memory, as throughout the analysis of 
knowledge, there are two very distinct problems, namely : 

(1) as to the nature of the present occurrence in knowing; 

(2) as to the relation of this occurrence to what is known. 
When we remember, the knowing is now, while what is 
known is in the past. Our two questions are, in the case 
of memory 

(1) What is the present occurrence when we re- 

member ? 

(2) What is the relation of this present occurrence 

to the past event which is remembered ? 

Of these two questions, only the first concerns the 
psychologist ; the second belongs to theory of knowledge. 
At the same time, if we accept the vague datum with 
which we began, to the effect that, in some sense, there 
is knowledge of the past, we shall have to find, if we can, 
such an account of the present occurrence in remembering 
as will make it not impossible for remembering to give 


us knowledge of the past. For the present, however, we 
shall do well to forget the problems concerning theory 
of knowledge, and concentrate upon the purely psycho- 
logical problem of memory. 

Between memory-image and sensation there is an 
intermediate experience concerning the immediate past. 
For example, a sound that we have just heard is present 
to us in a way which differs both from the sensation while 
we are hearing the sound and from the memory-image of 
something heard days or weeks ago. James states that 
it is this way of apprehending the immediate past that 
is " the original of our experience of pastness, from whence 
we get the meaning of the term " (Psychology, i, p. 604). 
Everyone knows the experience of noticing (say) that the 
clock has been striking, when we did not notice it while 
it was striking. And when we hear a remark spoken, 
we are conscious of the earlier words while the later ones 
are being uttered, and this retention feels different from 
recollection of something definitely past. A sensation 
fades gradually, passing by continuous gradations to the 
status of an image. This retention of the immediate 
past in a condition intermediate between sensation and 
image may be called " immediate memory." Everything 
belonging to it is included with sensation in what is called 
the " specious present/' The specious present includes 
elements at all stages on the journey from sensation to 
image. It is this fact that enables us to apprehend such 
things as movements, or the order of the words in a spoken 
sentence. Succession can occur within the specious 
present, of which we can distinguish some parts as earlier 
and others as later. It is to be supposed that the earliest 
parts are those that have faded most from their original 
force, while the latest parts are those that retain their 


full sensational character. At the beginning of a stimulus 
we have a sensation ; then a gradual transition ; and at 
the end an image. Sensations while they are fading are 
called " akoluthic " sensations. 1 When the process of 
fading is completed (which happens very quickly), we 
arrive at the image, which is capable of being revived 
on subsequent occasions with very little change. True 
memory, as opposed to " immediate memory," applies 
only to events sufficiently distant to have come to an 
end of the period of fading. Such events, if they are repre- 
sented by anything present, can only be represented by 
images, not by those intermediate stages, between sensa- 
tions and images, which occur during the period of fading. 

Immediate memory is important both because it provides 
experience of succession, and because it bridges the gulf 
between sensations and the images which are their copies. 
But it is now time to resume the consideration of true 

Suppose you ask me what I ate for breakfast this 
morning. Suppose, further, that I have not thought 
about ,my breakfast in the meantime, and that I did 
not, while I was eating it, put into words what it con- 
sisted of. In this case my recollection will be true 
memory, not habit-memory. The process of remembering 
will consist of calling up images of my breakfast, which 
will come to me with a feeling of belief such as distin- 
guishes memory-images from mere imagination-images. 
Or sometimes words may come without the intermediary 
of images ; but in this case equally the feeling of belief 
is essential. 

Let us omit from our consideration, for the present, 
the memories in which words replace images. These are 

1 See Semon, Die mnemischen Empfindungen, chap. vi. 


always, I think, really habit-memories, the memories that 
use images being the typical true memories. 

Memory-images and imagination-images do not differ 
in their intrinsic qualities, so far as we can discover. They 
differ by the fact that the images that constitute memories, 
unlike those that constitute imagination, are accom- 
panied by a feeling of belief which may be expressed in 
the words " this happened." The mere occurrence of 
images, without this feeling of belief, constitutes imagina- 
tion ; it is the element of belief that is the distinctive thing 
in memory. 1 

There are, if I am not mistaken, at least three different 
kinds' of belief-feeling, which we may call respectively 
memory, expectation and bare assent. In what I call 
bare assent, there is no time-element in the feeling of 
belief, though there may be in the content of what is 
believed. If I believe that Caesar landed in Britain in 
B.C. 55, the time-determination lies, not in the feeling of 
belief, but in what is believed. I do not remember the 
occurrence, but have the same feeling towards it as towards 
the announcement of an eclipse next year. But when I 
have seen a flash of lightning and am waiting for the 
thunder, I have a belief-feeling analogous to memory, 
except that it refers to the future : I have an image of 
thunder, combined with a feeling which may be expressed 
in the words : " this will happen." So, in memory, the 
pastness lies, not in the content of what is believed, but in 
the nature of the belief -feeling. I might have just the 
same images and expect their realization ; I might enter- 
tain them without any belief, as in reading a novel ; or 
I might entertain them together with a time-determina- 

' For belief of a specific kind, cf. Dorothy Wrinch "On the 
Nature of Memory/' Mind, January, 1920. 


tion, and give bare assent, as in reading history. I shall 
return to this subject in a later lecture, when we come 
to the analysis of belief. For the present, I wish to 
make it clear that a certain special kind of belief is the 
distinctive characteristic of memory. 

The problem as to whether memory can be explained 
as habit or association requires to be considered afresh 
in connection with the causes of our remembering some- 
thing. Let us take again the case of my being asked 
what I had for breakfast this morning. In this case the 
question leads to my setting to work to recollect. It is a 
little strange that the question should instruct me as to 
what it is that I am to recall. This has to do with under- 
standing words, which will be the topic of the next lecture ; 
but something must be said about it now. Our under- 
standing of the words " breakfast this morning " is a habit, 
in spite of the fact that on each fresh day they point to 
a different occasion. " This morning " does not, whenever 
it is used, mean the same thing, as " John " or "St. 
Paul's " does ; it means a different period of time on each 
different day. It follows that the habit which constitutes 
our understanding of the words " this morning " is not 
the habit of associating the words with a fixed object, 
but the habit of associating them with something having 
a fixed time-relation to our present. This morning has, 
to-day, the same time-relation to my present that yester- 
day morning had yesterday. In order to understand the 
phrase " this morning " it is necessary that we should 
have a way of feeling time-intervals, and that this feeling 
should give what is constant in the meaning of the words 
" this morning." This appreciation of time-intervals is, 
however, obviously a product of memory, not a presup- 
position of it. It will be better, therefore, if we wish to 



analyse the causation of memory by something not pre- 
supposing memory, to take some other instance than that 
of a question about " this morning." 

Let us take the case of coming into a familiar room 
where something has been changed say a new picture 
hung on the wall. We may at first have only a sense 
that something is unfamiliar, but presently we shall 
remember, and say " that picture was not on the wall 
before/' In order to make the case definite, we will 
suppose that we were only in the room on one former 
occasion. In this case it seems fairly clear what happens. 
The other objects in the room are associated, through 
the former occasion, with a blank space of wall where now 
there is a picture. They call up an image of a blank 
wall, which clashes with perception of the picture. The 
image is associated with the belief-feeling which we found 
to be distinctive of memory, since it can neither be 
abolished nor harmonized with perception. If the room 
had remained unchanged, we might have had only the 
feeling of familiarity without the definite remembering ; 
it is the change that drives us from the present to memory 
of the past. 

We may generalize this instance so as to cover the 
causes of many memories. Some present feature of the 
environment is associated, through past experiences, with 
something now absent ; this absent something comes before 
us as an image, and is contrasted with present sensation. 
In cases of this sort, habit (or association) explains why 
the present feature of the environment brings up the 
memory-image, but it does not explain the memory- 
belief. Perhaps a more complete analysis could explain 
the memory-belief also on lines of association and habit, 
but the causes of beliefs are obscure, and we cannot in- 


vestigate them yet. For the present we must content 
ourselves with the fact that the memory-image can be 
explained by habit. As regards the memory-belief, we 
must, at least provisionally, accept Bergson's view that 
it cannot be brought under the head of habit, at any 
rate when it first occurs, i.e. when we remember some- 
thing we never remembered before. 

We must now consider somewhat more closely the con- 
tent of a memory-belief. The memory-belief confers 
upon the memory-image something which we may call 
" meaning " ; it makes us feel that the image points to 
an object which existed in the past. In order to deal 
with this topic we must consider the verbal expression 
of the memory-belief. We might be tempted to put the 
memory-belief into the words : " Something like this 
image occurred/' But such words would be very far 
from an accurate translation of the simplest kind of 
memory-belief. " Something like this image 1 ' is a very 
complicated conception. In the simplest kind of memory 
we are not aware of the difference between an image and 
the sensation which it copies, which may be called its 
" prototype." When the image is before us, we judge 
rather " this occurred." The image is not distinguished 
from the object which existed in the past : the word " this " 
covers both, and enables us to have a memory-belief which 
does not introduce the complicated notion " something 
like this." 

It might be objected that, if we judge " this occurred " 
when in fact " this " is a present image, we judge falsely, 
and the memory-belief, so interpreted, becomes deceptive. 
This, however, would be a mistake, produced by attempt- 
ing to give to wprds a precision which they do not possess 
when used by unsophisticated people. It is true that the 


image is not absolutely identical with its prototype, and 
if the word " this " meant the image to the exclusion of 
everything else, the judgment " this occurred " would be 
false. But identity is a precise conception, and no word, 
in ordinary speech, stands for anything precise. Ordinary 
speech does not distinguish between identity and close 
similarity. A word always applies, not only to one 
particular, but to a group of associated particulars, which 
are not recognized as multiple in common thought or 
speech. Thus primitive memory, when it judges that 
" this occurred," is vague, but not false. 

Vague identity, which is really close similarity, has 
been a source of many of the confusions by which 
philosophy has lived. Of a vague subject, such as a 
" this," which is both an image and its prototype, con- 
tradictory predicates are true simultaneously : this existed 
and does not exist, since it is a thing remembered, but 
also this exists and did not exist, since it is a present 
image. Hence Bergson's interpenetration of the present 
by the past, Hegelian continuity and identity-in-diversity, 
and a host of other notions which are thought to be pro- 
found because they are obscure and confused. The con- 
tradictions resulting from confounding image and proto- 
type in memory force us to precision* But when we 
become precise, our remembering becomes different from 
that of ordinary life, and if we forget this we shall go 
wrong in the analysis of ordinary memory. 

Vagueness and accuracy are important notions, which 
it is very necessary to understand. Both are a matter of 
degree. All thinking is vague to some extent, and com- 
plete accuracy is a theoretical ideal not practically attain- 
able. To understand what is meant by accuracy, it will 
be well to consider first instruments of measurement, 


such as a balance or a thermometer. These are said to 
be accurate when they give different results for very 
slightly different stimuli. 1 A clinical thermometer is 
accurate when it enables us to detect very slight differences 
in the temperature of the blood. We may say generally 
that an instrument is accurate in proportion as it reacts 
differently to very slightly different stimuli. When a 
small difference of stimulus produces a great difference of 
reaction, the instrument is accurate ; in the contrary case 
it is not. 

Exactly the same thing applies in defining accuracy of 
thought or perception. A musician will respond differ- 
ently to very minute differences in playing which would 
be quite imperceptible to the ordinary mortal. A negro 
can see the difference between one negro and another : 
one is his friend, another his enemy. But to us 
such different responses are impossible : we can merely 
apply the word " negro " indiscriminately. Accuracy 
of response in regard to any particular kind of stimulus 
is improved by practice. Understanding a language is a 
case in point. Few Frenchmen can hear any difference 
between the sounds " hall " and " hole," which produce 
quite different impressions upon us. The two statements 
" the hall is full of water " and " the hole is full of water " 
call for different responses, and a hearing which cannot 
distinguish between them is inaccurate or vague in this 

Precision and vagueness in thought, as in perception, 
depend upon the degree of difference between responses to 
more or less similar stimuli. In the case of thought, the 
response does not follow immediately upon the sensational 

1 This is a necessary but not a sufficient condition. The subject 
of accuracy and vagueness will be considered again in Lecture XIII. 


stimulus, but that makes no difference as regards our 
present question. Thus to revert to memory : A memory 
is " vague " when it is appropriate to many different 
occurrences : for instance, " I met a man " is vague, since 
any man would verify it. A memory is " precise " when 
the occurrences that would verify it are narrowly circum- 
scribed : for instance, " I met Jones " is precise as com- 
pared to "I met a man." A memory is " accurate " 
when it is both precise and true, i.e. in the above instance, 
if it was Jones I met. It is precise even if it is false, 
provided some very definite occurrence would have been 
required to make it true. 

It follows from what has been said that a vague thought 
has more likelihood of being true than a precise one. 
To try and hit an object with a vague thought is like 
trying to hit the bull's eye with a lump of putty : when 
the putty reaches the target, it flattens out all over it, 
and probably covers the bull's eye along with the rest. 
To try and hit an object with a precise thought is like 
trying to hit the bull's eye with a bullet. The advantage 
of the precise thought is that it distinguishes between 
the bull's eye and the rest of the target. For example, 
if the whole target is represented by the fungus family 
and the bull's eye by mushrooms, a vague thought which 
can only hit the target as a whole is not much use from 
a culinary point of view. And when I merely remember 
that I met a man, my memory may be very inadequate to 
my practical requirements, since it may make a great 
difference whether I met Brown or Jones. The memory 
" I met Jones " is relatively precise. It is accurate if I 
met Jones, inaccurate if I met Brown, but precise in 
either case as against the mere recollection that I met 
a man. 


The distinction between accuracy and precision is, 
however, not fundamental. We may omit precision from 
out thoughts and confine ourselves to the distinction 
between accuracy and vagueness. We may then set up 
the following definitions : 

An instrument is "reliable*' with respect to a given 
set of stimuli when to stimuli which are not relevantly 
different it gives always responses which are not relevantly 

An instrument is a " measure " of a set of stimuli which 
are serially ordered when its responses, in all cases where 
they are relevantly different, are arranged in a series in 
the same order. 

The " degree of accuracy " of an instrument which is 
a reliable measurer is the ratio of the difference of response 
to the difference of stimulus in cases where the difference 
of stimulus is small. 1 That is to say, if a small difference 
of stimulus produces a great difference of response, the 
instrument is very accurate ; in the contrary case, very 

A, mental response is called " vague " in proportion to 
its lack of accuracy, or rather precision. 

These definitions will be found useful, not only in the 
case of memory, but in almost all questions concerned 
with knowledge. 

It should be observed that vague beliefs, so far from 
being necessarily false, have a better chance of truth 
than precise ones, though their truth is less valuable 
than that of precise beliefs, since they do not distinguish 
between occurrences which may differ in important ways. 

The whole of the above discussion of vagueness and 

* Strictly speaking, the limit of this, i.e. the derivative of the 
response with respect to the stimulus, 


accuracy was occasioned by the attempt to interpret the 
word " this " when we judge in verbal memory that " this 
occurred." The word " this," in such a judgment, is a 
vague word, equally applicable to the present memory- 
image and to the past occurrence which is its prototype. 
A vague word is not to be identified with a general word, 
though in practice the distinction may often be blurred. 
A word is general when it is understood to be applicable 
to a number of different objects in virtue of some common 
property. A word is vague when it is in fact applicable 
to a number of different objects because, in virtue of 
some common property, they have not appeared, to the 
person using the word, to be distinct. I emphatically do 
not mean that he has judged them to be identical, but 
merely that he has made the same response to them all 
and has not judged them to be different. We may com- 
pare a vague word to a jelly and a general word to a heap 
of shot. Vague words precede judgments of identity and 
difference ; both general and particular words are sub- 
sequent to such judgments. The word " this " in the 
primitive memory-belief is a vague word, not a general 
word ; it covers both the image and its prototype because 
the two are not distinguished. 1 
But we have not yet finished our analysis of the 

* On the vague and the general cf . Ribot : Evolution of General 
Ideas, Open Court Co., 1899, p. 32 : " The sole permissible formula 
is this : Intelligence progresses from the indefinite to the definite. 
If ' indefinite ' is taken as synonymous with general, it may be 
said that the particular does not appear at the outset, but neither 
does the general in any exact sense : the vague would be more 
appropriate. In other words, no sooner has tlie intellect progressed 
beyond the moment of perception and of its immediate repro- 
duction in memory, than the generic image makes its appearance, 
i.e. a state intermediate between the particular and the general, 
participating in the nature of the one and of the other a confused 


memory-belief. The tense in the belief that " this 
occurred " is provided by the nature of the belief -feeling 
involved in memory ; the word " this/' as we have seen, 
has a vagueness which we have tried to describe. But 
we must still ask what we mean by " occurred/' The 
image is, in one sense, occurring now ; and therefore we 
must find some other sense in which the past event 
occurred but the image does not occur. 

There are two distinct questions to be asked : (i) What 
causes us to say that a thing occurs ? (2) What are we 
feeling when we say this ? As to the first question, in 
the crude use of the word, which is what concerns us, 
memory-images would not be said to occur ; they would 
not be noticed in themselves, but merely used as signs of 
the past event. Images are " merely imaginary " ; they 
have not, in crude thought, the sort of reality that belongs 
to outside bodies. Roughly speaking, " real " things 
would be those that can cause sensations, those that have 
correlations of the sort that constitute physical objects. 
A thing is said to be " real " or to " occur " when it fits 
into a context of such correlations. The prototype of 
our memory-image did fit into a physical context, while 
our memory-image does not. This causes us to feel 
that the prototype was " real/' while the image is 
" imaginary/' 

But the answer to our second question, namely as to 
what we are feeling when we say a thing " occurs " or is 
" real," must be somewhat different. We do not, unless 
we are unusually reflective, think about the presence or 
absence of correlations : we merely have different feelings 
which, intellectualized, may be represented as expectations 
of the presence or absence of correlations. A thing which 
" feels real " inspires us with hopes or fears, expectations 


or curiosities, which are wholly absent when a thing 
"feels imaginary." The feeling of reality is a feeling 
akin to respect : it belongs primarily to whatever can do 
things to us without our voluntary co-operation. This 
feeling of reality, related to the memory-image, and 
referred to the past by the specific kind of belief-feeling 
that is characteristic of memory, seems to be what con- 
stitutes the act of remembering in its pure form. 

We may now summarize our analysis of pure memory. 

Memory demands (a) an image, (b) a belief in past 
existence. The belief may be expressed in the words 
" this existed." 

The belief, like every other, may be analysed into 
(i) the believing, (2) what is believed. The believing is 
a specific feeling or sensation or complex of sensations, 
different from expectation or bare assent in a way that 
makes the belief refer to the past ; the reference to the 
past lies in the belief- feeling, not in the content believed. 
There is a relation between the belief-feeling and the 
content, making the belief-feeling refer to the content, 
and expressed by saying that the content is what is 

The content believed may or may not be expressed in 
words. Let us take first the case when it is not. In 
that case, if we are merely remembering that something 
of which we now have an image occurred, the content 
consists of (a) the image, (b) the feeling, analogous to 
respect, which we translate by saying that something is 
" real " as opposed to " imaginary/' (c) a relation between 
the image and the feeling of reality, of the sort expressed 
when we say that the feeling refers to the image. This 
content does not contain in itself any time-determination : 
the time-determination lies in the nature of the belief- 


feeling, which is that called " remembering " or (better) 
" recollecting/' It is only subsequent reflection upon this 
reference to the past that makes us realize the distinction 
between the image and the event recollected. When we 
have made this distinction, we can say that the image 
" means " the past event. 

The content expressed in words is best represented by 
the words " the existence of this," since these words do 
not involve tense, which belongs to the belief-feeling, not 
to the content. Here " this " is a vague term, covering 
the memory-image and anything very like it, including 
its prototype. " Existence " expresses the feeling of a 
" reality " aroused primarily by whatever can have 
effects upon us without our voluntary co-operation. The 
word " of " in the phrase " the existence of this " repre- 
sents the relation which subsists between the feeling of 
reality and the " this." 

This analysis of memory is probably extremely faulty, 
but I do not know how to improve it. 

NOTE. When I speak of a feeling of belief, I use the 
word "feeling" in a popular sense, to cover a sensation 
or an image or a complex of sensations or images or both ; 
I use this word because I do not wish to commit myself 
to any special analysis of the belief-feeling. 


THE problem with which we shall be concerned in this 
lecture is the problem of determining what is the relation 
called " meaning." The word " Napoleon/' we say, 
" means " a certain person. In saying this, we are assert- 
ing a relation between the word " Napoleon " and the 
person so designated. It is this relation that we must 
now investigate. 

Let us first consider what sort of object a word is when 
considered simply as a physical thing, apart from its 
meaning. To begin with, there are many instances of 
a word, namely all the different occasions when it is 
employed. Thus a word is not something unique and 
particular, but a set of occurrences. If we confine our- 
selves to spoken words, a word has two aspects, accord- 
ing as we regard it from the point of view of the speaker 
or from that of the hearer. From the point of view of 
the speaker, a single instance of the use of a word consists 
of a certain set of movements in the throat and mouth, 
combined with breath. From the point of view of the 
hearer, a single instance of the use of a word consists of 
a certain series of sounds, each being approximately 
represented by a single letter in writing, though in prac- 
tice a letter may represent several sounds, or several 



letters may represent one sound. The connection 
between the spoken word and the word as it reaches 
the hearer is causal. Let us confine ourselves to the 
spoken word, which is the more important for the analysis 
of what is called " thought." Then we may say that a 
single instance of the spoken word consists of a series of 
movements, and the word consists of a whole set of such 
series, each member of the set being very similar to each 
other member. That is to say, any two instances of the 
word " Napoleon " are very similar, and each instance 
consists of a series of movements in the mouth. 

A single word, accordingly, is by no means simple : 
it is a class of similar series of movements (confining 
ourselves still to the spoken word). The degree of simi- 
larity required cannot be precisely defined : a man may 
pronounce the word " Napoleon " so badly that it can 
hardly be determined whether he has really pronounced 
it or not. The instances of a word shade off into other 
movements by imperceptible degrees. And exactly analo- 
gous observations apply to words heard or written or 
read. But in what has been said so far we have not even 
broached the question of the definition of a word, since 
" meaning " is clearly what distinguishes a word from other 
sets of similar movements, and " meaning " remains to 
be defined. 

It is natural to think of the meaning of a word as some- 
thing conventional. This, however, is only true with 
great limitations. A new word can be added to an exist- 
ing language by a mere convention, as is done, for instance* 
with new scientific terms. But the basis of a language 
is not conventional, either from the point of view of the 
individual or from that of the community. A child 
learning to speak is learning habits and associations 


which are just as much determined by the environment 
as the habit of expecting dogs to bark and cocks to crow. 
The community that speaks a language has learnt it, 
and modified it by processes almost all of which are not 
deliberate, but the results of causes operating according 
to more or less ascertainable laws. If we trace any 
Indo-European language back far enough, we arrive 
hypothetically (at any rate according to some authorities) 
at the stage when language consisted only of the roots 
out of which subsequent words have grown. How these 
roots acquired their meanings is not known, but a con- 
ventional origin is clearly just as mythical as the social 
contract by which Hobbes and Rousseau supposed civil 
government to have been established. We can hardly 
suppose a parliament of hitherto speechless elders meeting 
together and agreeing to call a cow a cow and a wolf a 
wolf. The association of words with their meanings 
must have grown up by some natural process, though at 
present the nature of the process is unknown. 

Spoken and written words are, of course, not the only 
way of conveying meaning. A large part of one of 
Wundt's two vast volumes on language in his Volker- 
psychologie is concerned with gesture-language. Ants 
appear to be able to communicate a certain amount of 
information by means of their antennae. Probably 
writing itself, which we now regard as merely a way of 
representing speech, was originally an independent lan- 
guage, as it has remained to this day in China. Writing 
seems to have consisted originally of pictures, which 
gradually became conventionalized, coming- in time to 
represent syllables, and finally letters on the telephone 
principle of " T for Tommy." But it would seem that 
writing nowhere began as an attempt to represent speech : 


it began as a direct pictorial representation of what was 
to be expressed. The essence of language lies, not in 
the use of this or that special means of communication, 
but in the employment of fixed associations (however 
these may have originated) in order that something now 
sensible a spoken word, a picture, a gesture, or what 
not may call up the " idea " of something else. When- 
ever this is done, what is now sensible may be called 
a " sign " or " symbol/ 1 and that of which it is intended 
to call up the " idea " may be called its " meaning." 
This is a rough outline of what constitutes " meaning." 
But we must fill in the outline in various ways. And, 
since we. are concerned with what is called " thought/ 1 
we must pay more attention than we otherwise should 
do to the private as opposed to the social use of language. 

our thoughts, _and it is this 

aspect of language that is of most importance to us in 
our present inquiry. We are almost more concerned 
with the internal speech that is never uttered than we are 
with the things said out loud to other people. 

When, we ask what constitutes meaning, we are not 
asking what is the meaning of this or that particular 
word. The word " Napoleon " means a certain indi- 
vidual ; but we are asking, not who is the individual 
meant, but what is the relation of the word to the indi- 
vidual which makes the one mean the other. But just 
as it is useful to realize the nature of a word as part of 
the physical world, so it is useful to realize the sort oi 
thing that a word may mean. When we are clear both 
as to what a word is in its physical aspect, and as to what 
sort of thing it can mean, we are in a better position to 
discover the relation of the two which is meaning. 

The things that words mean differ more than words 


do. Thete are different sorts of words, distinguished by 
the grammarians ; and there are logical distinctions, 
which are connected to some extent, though not so closely 
as was formerly supposed, with the grammatical distinc- 
tions of parts of speech. It is easy, however, to be misled 
.by grammar, particularly if all the languages we know 
belong to one family. In some languages, according to 
some authorities, the distinction of parts of speech does 
not exist ; in many languages it is widely different from 
that to which we are accustomed in the Indo-European 
languages. These facts have to be borne in mind if we are 
to avoid giving metaphysical importance to mere accidents 
of (Mir own speech. 

In considering what words mean, it is natural to start 
with proper names, and we will again take " Napoleon " 
as our instance. We commonly imagine, when we use a 
proper name, that we mean one definite entity, the 
particular individual who was called " Napoleon." But 
what we know as a person is not simple There may be 
a single simple ego which was Napoleon, and remained 
strictly identical from his birth to his death. There is 
no way of proving that this cannot be the case, but there 
is also not the slightest reason to suppose that it is the 
case. Napoleon as he was empirically known consisted 
of a series of gradually changing appearances : first a 
squalling baby, then a boy, then a ftlijn and beautiful 
youth, then a fat and slothful person very magnificently 
dressed. This series of appearances, and various occur- 
rences having certain kinds of causal connections with 
them, constitute Napoleon as empirically known, and 
therefore are Napoleon in so far as he forms part of the 
experienced world. Napoleon is a complicated series of 
occurrences, bound together by causal laws, not, like 


instances of a word, by similarities. For although a 
person changes gradually, and presents similar appear- 
ances on two nearly cont^gpraneous occasions, it is not 
these similarities that constitute the person, ias appears 
from the Gomedy of Errors for example. 

Thus in the case of a proper name, while the word is 
a set of similar series of movements, what it means is a 
series of occurrences bound together by causal laws of 
that special kind that makes the occurrences taken 
together constitute what we call one person, or one animal 
or thing, in case the name applies to an animal or thing 
instead of to a person. Neither the word nor what it 
names is one of the ultimate indivisible constituents of 
the world. x> In language there is no direct way of desig- 
nating one of the ultimate brief existents that go to make 
up the collections we call things or persons. If we want 
to speak of such existents which hardly happens except 
in philosophy we have to do it by means of some 
elaborate phrase, such as " the visual sensation which 
occupied the centre of my field of vision at noon on 
January I, 1919." Such ultimate simples I call " par- 
ticulars." Particulars might have proper names, and no 
doubt would have if language had been invented by 
scientifically trained observers for purposes of philosophy 
and logic. But as language was invented for practical 
ends, particulars have remained one and all without a 

We are not, in practice, much concerned with the 
actual particulars that come into our experience in sensa- 
tion ; we are concerned rather with whole systems to 
which the particulars belong and of which they are signs. 
What we see makes us say " Hullo, there's Jones," and 
the fact that what we see is a sign of Jones (which is the 



case because it is one of the particulars that make up 
Jones) is more interesting to us than the actual particular 
itself. Hence we give the name " Jones " to the whole 
set of particulars, but do not trouble to give separate 
names to the separate particulars that make up the 

Passing on from proper names, we come next to general 
names, such as " man," " cat/' " triangle. 1 ' A word such 
as " man " means a whole class of such collections of 
particulars as have proper names. The several members 
of the class are assembled together in virtue of some 
similarity or common property. All men resemble each 
other in certain important respects ; hence we want a 
word which shall be equally applicable to all of them. 
We only give proper names to the individuals of a species 
when they differ inter se in practically important respects. 
In other cases we do not do this. A poker, for instance, 
is just a poker ; we do not call one " John " and another 
" Peter." 

There is a large class of words, such as " eating," " walk- 
ing," ''speaking," which mean a set of similar occurrences. 
Two instances of walking have the same name because 
they resemble each other, whereas two instances of Jones 
have the same name because they are causally connected. 
In practice, however, it is difficult to make any precise 
distinction between a word such as " walking " and a 
general name such as " man." One instance of walking 
cannot be concentrated into an instant : it is a process 
in time, in which there is a causal connection between 
the earlier and later parts, as between the earlier and later 
parts of Jones. Thus an instance of walking differs from 
an instance of man solely by the fact that it has a shorter 
life. There is a notion that an instance of walking, as 


compared with Jones, is unsubstantial, but this seems to 
be a mistake. We think that Jones walks, and that there 
could not be any walking unless there were somebody 
like Jones to perform the walking. But it is equally 
true that there could be no Jones unless there were some- 
thing like walking for him to do. The notion that actions 
are performed by an agent is liable to the same kind of 
criticism as the notion that thinking needs a subject or 
ego, which we rejected in Lecture I. To say that it is 
Jones who is walking is merely to say that the walking 
in question is part of the whole series of occurrences which 
is Jones. There is no logical impossibility in walking 
occurring as an isolated phenomenon, not forming part of 
any such series as we call a " person." 

We may therefore class with " eating," " walking," 
" speaking " words such as " rain," " sunrise," " light- 
ning," which do not denote what would commonly be 
called actions. These words illustrate, incidentally, how 
little we can trust to the grammatical distinction of parts 
of speech, since the substantive " rain " and the verb 
" to rain " denote precisely the same class of meteoro- 
logical occurrences. The distinction between the class of 
objects denoted by such a word and the class of objects 
denoted by a general name such as " man," " vegetable," 
or " planet," is that the sort of object which is an instance 
of (say) " lightning " is much simpler than (say) an indi- 
vidual man. (I am speaking of lightning as a sensible 
phenomenon, not as it is described in physics.) The 
distinction is one of degree, not of kind. But there is, 
from the point of view of ordinary thought, a great differ- 
ence between a process which, like a flash of lightning, 
can be wholly comprised within one specious present 
and a process which, like the life of a man, has to be pieced 


together by observation and memory and the appre- 
hension of causal connections. We may say broadly, 
therefore, that a word of the kind we have been discussing 
denotes a set of similar occurrences, each (as a rule) much 
more brief and less complex than a person or thing. Words 
themselves, as we have seen, are sets of similar occurrences 
of this kind. Thus there is more logical affinity between 
a word and what it means in the case of words of our present 
sort than in any other case. 

There is no very great difference between such words 
as we have just been considering and words denoting 
qualities, such as " white " or "round." The chief 
difference is that words of this latter sort do not denote 
processes, however brief, but static features of the world. 
Snow falls, and is white ; the falling is a process, the 
whiteness is not. Whether there is a universal, called 
" whiteness," or whether white things are to be defined 
as those having a certain kind of similarity to a standard 
thing, say freshly fallen snow, is a question which need 
not concern us, and which I believe to be strictly insoluble. 
For our purposes, we may take the word " white " as 
denoting a certain set of similar particulars or collections 
of particulars, the similarity being in respect of a static 
quality, not of a process. 

From the logical point of view, a very important class 
of words are those that express relations, such as "in," 
" above," " before," " greater," and so on. The meaning 
of one of these words differs very fundamentally from the 
meaning of one of any of our previous classes, being 
more abstract and logically simpler than any of them. 
If our business were logic, we should have to spend much 
time on these words. But as it is psychology that con- 
cerns us, we will merely note their special character and 


pass on, since the logical classification of words is not 
our main business. 

We will consider next the question what is implied 
by saying that a person " understands " a word, in the 
sense in which one understands a word in one's own 
language, but not in a language of which one is ignorant. 
We may say that a person understands a word when 
(a) suitable circumstances make him use it, (b) the hearing 
of it causes suitable behaviour in him. We may call 
these two active and passive understanding respectively. 
Dogs often have passive understanding of some words, 
but not active understanding, since they cannot use 

It is not necessary, in order that a man should " under- 
stand " a word, that he should " know what it means," 
in the sense of being able to say " this word means so- 
and-so." Understanding words does not consist in know- 
ing their dictionary definitions, or in being able to specify 
the objects to which they are appropriate. Such under- 
standing as this may belong to lexicographers and 
students, but not to ordinary mortals in ordinary life. 
Understanding language is more like understanding 
cricket * : it is a matter of habits, acquired in oneself 
and rightly presumed in others. To say that a word has a 
meaning is not to say that those who use the word correctly 
have ever thought out what the meaning is : the use of 
the word comes first, and the meaning is to be distilled 
out of it by observation and analysis. Moreover, the 
meaning of a word is not absolutely definite : there is 

1 This point of view, extended to the analysis of " thought " 
is urged with great force by J. B. Watson, both in his Behavior, 
and in Psychology from the Standpoint of a Behaviorist (Lippincott, 
1919), chap. ix. 


always a greater or less degree of vagueness. The mean- 
ing is an area, like a target : it may have a bull's eye, 
but the outlying parts of the target are still more or less 
within the meaning, in a gradually diminishing degree 
as we travel further from the bull's eye. As language 
grows more precise, there is less and less of the target 
outside the bull's eye, and the bull's eye itself grows 
smaller and smaller ; but the bull's eye never shrinks to 
a point, and there is always a doubtful region, however 
small, surrounding it. 1 

A word is used " correctly " when the average hearer 
will be affected by it in the way intended. This is a 
psychological, not a literary, definition of " correctness." 
The literary definition would substitute, for the average 
hearer, a person of high education living a long time ago ; 
the purpose of this definition is to make it difficult to speak 
or write correctly. 

The relation of a word to its meaning is of the nature 
of a causal law governing our use of the word and our 
actions when we hear it used. There is no more reason 
why a person who uses a word correctly should be able 
to tell what it means than there is why a planet which is 
moving correctly should know Kepler's laws. 

To illustrate what is meant by " understanding " 
words and sentences, let us take instances of various 

* On the understanding of words, a very admirable little book 
is Ribot's Evolution of General Ideas, Open Court Co., 1899. Ribot 
says (p. 131) : " We learn to understand a concept as we learn 
to walk, dance, fence or play a musical instrument : it is a habit, 
i.e. an organized memory. General terms cover an organized, 
latent knowledge which is the hidden capital without which we 
should be in a state of bankruptcy, manipulating false money or 
paper of no value. General ideas are habits in the intellectual 


Suppose you are walking in London with an absent- 
minded friend, and while crossing a street you say, " Look 
out, there's a motor coming/' He will glance round and 
jump aside without the need of any " mental " inter- 
mediary. There need be no " ideas/' but only a stiffening 
of the muscles, followed quickly by action. He " under- 
stands " the words, because he does the right thing. Such 
" understanding " may be taken to belong to the nerves 
and brain, being habits which they have acquired while 
the language was being learnt. Thus understanding in 
this sense may be reduced to mere physiological causal 

If you say the same thing to a Frenchman with a slight 
knowledge of English he will go through some inner 
speech which may be represented by " Que dit-il ? Ah, 
oui, une automobile ! " After this, the rest follows as 
with the Englishman. Watson would contend that the 
inner speech must be incipiently pronounced ; we should 
argue that it might be merely imaged. But this point 
is not important in the present connection. 

If you say the same thing to a child who does not yet 
know the word " motor," but does know the other words 
you are using, you produce a feeling of anxiety and doubt : 
you will have to point and say, " There, that's a motor." 
After that the child will roughly understand the word 
" motor," though he may include trains and steam-rollers, 
If this is the first time the child has heard the word 
" motor," he may for a long time continue to recall 
this scene when he hears the word. 

So far we have found four ways of understanding 
words : 

(1) On suitable occasions you use the word properly. 

(2) When you hear it you act appropriately 


(3) You associate the word with another word 

(say in a different language) which has the 
appropriate effect on behaviour. 

(4) When the word is being first learnt, you may 

associate it with an object, which is what 
it " means," or a representative of various 
objects that it " means." 

In the fourth case, the word acquires, through asso- 
ciation, some of the same causal efficacy as the object. 
The word " motor " can make you leap aside, just as the 
motor can, but it cannot break your bones. The effects 
which a word can share with its object are those which 
proceed according to laws other than the general laws of 
physics, i.e. those which, according to our terminology, 
involve vital movements as opposed to merely mechanical 
movements. The effects of a word that we understand 
are always mnemic phenomena in the sense explained in 
Lecture IV, in so far as they are identical with, or similar 
to, the effects which the object itself might have. 
^So far, all the uses of words that we have considered 
can be accounted for on the lines of behaviourism. 

But so far we have only considered what may be called 
the " demonstrative " use of language, to point out some 
feature in the present environment. This is only one of 
the ways in which language may be used. There are also 
its narrative and imaginative uses, as in history and 
novels. Let us take as an instance the telling of some 
remembered event. 

We spoke a moment ago of a child who hears the word 
" motor " for the first time when crossing a street along 
which a motor-car is approaching. On a later occasion, 
we will suppose, the child remembers the incident and 


relates it to someone else. In this case, both the active 
and passive understanding of words is different from what 
it is when words are used demonstratively. The child is 
not seeing a motor, but only remembering one ; the 
hearer does not look round in expectation of seeing a 
motor coming, but " understands " that a motor came at 
some earlier time. The whole of this occurrence is much 
more difficult to account for on behaviourist lines. It is 
clear that, in so far as the child is genuinely remembering, 
he has a picture of the past occurrence, and his words 
are chosen so as to describe the picture ; and in so far 
as the hearer is genuinely apprehending what is said, the 
hearer is acquiring a picture more or less like that of the 
child. It is true that this process may be telescoped 
through the operation of the word-habit. The child may 
not genuinely remember the incident, but only have the 
habit of the appropriate words, as in the case of a poem 
which we know by heart, though we cannot remember 
learning it. And the hearer also may only pay attention to 
the words, and not call up any corresponding picture. 
But it is, nevertheless, the possibility of a memory-image 
in the child and an imagination-image in the hearer that 
makes the essence of the narrative " meaning " of the 
words. In so far as this is absent, the words are mere 
counters, capable of meaning, but not at the moment 
possessing it. / 

Yet this might perhaps be regarded as something of 
an over-statement. The words alone, without the use of 
images, may cause appropriate emotions and appropriate 
behaviour. The words have been used in an environment 
which produced certain emotions; by a telescoped pro- 
cess, the words alone are now capable of producing 
similar emotions. On these lines it might be sought to 


show that images are unnecessary. I do not believe, 
however, that we could account on these lines for the 
entirely different response produced by a narrative and 
by a description of present facts. Images, as contrasted 
with sensations, are the response expected during a narra- 
tive ; it is understood that present action is not called 
for. Thus it seems that we must maintain our distinction : 
words used demonstratively describe and are intended to 
lead to sensations, while the same words used in narrative 
describe and are only intended to lead to images. 

We have thus, in addition to our four previous ways 
in which words can mean, two new ways, namely the 
wajr of memory and the way of imagination. That is 
to say : 

(5) Words may be used to describe or recall a memory- 

image : to describe it when it already exists, 
or to recall it when the words exist as a habit 
and are known to be descriptive of some past 

(6) Words may be used to describe or create an 

imagination-image : to describe it, for ex- 
ample, in the case of a poet or novelist, or 
to create it in the ordinary case for giving 
information though, in the latter case, it is 
intended that the imagination-image, when 
created, shall be accompanied by belief that 
something of the sort occurred. 

These two ways of using words, including their occur- 
rence in inner speech, may be spoken of together as the 
use of words in " thinking/' If we are right, the use of 
words in thinking depends, at least in its origin, upon 
images, and cannot be fully dealt with on behaviourist 


lines. And this is really the most essential function of 
words, namely that, originally through their connection 
with images, they bring us into touch with what is remote 
in time or space. When they operate without the medium 
of images, this seems to be a telescoped process. Thus 
the problem of the meaning of words is brought into con- 
nection with the problem of the meaning of images. 

To understand the function that words perform in 
what is called " thinking," we must understand both the 
causes and the effects of their occurrence. The causes 
of the occurrence of words require somewhat different 
treatment according as the object designated by the 
word is sensibly present or absent. When the object is 
present, it may itself be taken as the cause of the word, 
through association. But when it is absent there is more 
difficulty in obtaining a behaviourist theory of the occur- 
rence of the word. The language-habit consists not 
merely in the use of words demonstratively, but also in 
their use to express narrative or desire. Professor Watson, 
in his account of the acquisition of the language-habit, 
pays very little attention to the use of words in narrative 
and desire. He says (Behavior, pp. 329-330) : 

" The stimulus (object) to which the child often responds, 
a box, e.g. by movements such as opening and closing 
and putting objects into it, may serve to illustrate our 
argument. The nurse, observing that the child reacts 
with his hands, feet, etc., to the box, begins to say ' box ' 
when the child is handed the box, ' open box ' when the 
childs opens it, ' close box ' when he closes it, and ' put 
doll in box ' when that act is executed. This is repeated 
over and over again. In the process of time it comes 
about that without any other stimulus than that of the 
box which originally called out the bodily habits, he 


begins to say ' box ' when he sees it, ' open box ' when 
he opens it, etc. The visible box now becomes a stimulus 
capable of releasing either the bodily habits or the word- 
habit, i.e. development has brought about two things : 
(i) a series of functional connections among arcs which 
run from visual receptor to muscles of throat, and (2) a 
series of already earlier connected arcs which run from 
the same receptor to the bodily muscles. . . . The object 
meets the child's vision. He runs to it and tries to reach 
it and says ' box.' . . . Finally the word is uttered 
without the movement of going towards the box being 
executed. . . . Habits are formed of going to the box 
when the arms are full of toys. The child has been taught 
to deposit them there. When his arms are laden with toys 
and no box is there, the word-habit arises and he calls 
' box ' ; it is handed to him, and he opens it and deposits 
the toys therein. This roughly marks what we would call 
the genesis of a true language-habit " (pp. 329-330). l 

We need not linger over what is said in the above 
passage as to the use of the word " box " in the presence 
of the box. But as to its use in the absence of the box, 
there is only one brief sentence, namely : " When his 
arms are laden with toys and no box is there, the word- 
habit arises and he calls ' box/ " This is inadequate as 
it stands, since the habit has been to use the word when 
the box is present, and we have to explain its extension 
to cases in which the box is absent. 

Having admitted images, we may say that the word 
" box," in the absence of the box, is caused by an image 
of the box. This may or may not be true in fact, it is 

true in some cases but not in others. Even, however, if 

1 Just the same account of language is given in Professor Wat- 
son's more recent book (reference above). 


it were true in all cases, it would only slightly shift our 
problem : we should now have to ask what causes an 
image of the box to arise. We might be inclined to say 
that desire for the box is the cause. But when this view 
is investigated, it is found that it compels us to suppose 
that the box can be desired without the child's having 
either an image of the box or the word " box." This will 
require a theory of desire which may be, and I think is, 
in the main true, but which removes desire from among 
things that actually occur, and makes it merely a con- 
venient fiction, like force in mechanics. 1 With such a 
view, desire is no longer a true cause, but merely a short 
way of describing certain processes. 

In order to explain the occurrence of either the word 
or the image in the absence of the box, we have to assume 
that there is something, either in the environment or in 
our own sensations, which has frequently occurred at 
about the same time as the word " box/ 1 One of the 
laws which distinguish psychology (or nerve-physiology ?) 
from physics is the law that, when two things have fre- 
quently existed in close temporal contiguity, either comes 
in time to cause the other. 2 This is the basis both of 
habit and of association. Thus, in our case, the arms full 
of toys have frequently been followed quickly by the 
box, and the box in turn by the word " box." ' The box 
itself is subject to physical laws, and does not tend to be 
caused by the arms full of toys, however often it may in 
the past have followed them always provided that, in 
the case in question, its physical position is such that 

1 See Lecture III, above. 

* For a more exact statement of this law, with the limitations 
suggested by experiment, see A. Wohlgemuth, " On Memory and 
the Direction of Associations," British Journal of Psychology, 
vol. v, part iv (March, 1913). 


voluntary movements cannot lead to it. But the word 
" box " and the image of the box are subject to the law 
of habit ; hence it is possible for either to be caused by 
the arms full of toys. And we may lay it down generally 
that, whenever we use a word, either aloud or in inner 
speech, there is some sensation or image (either of which 
may be itself a word) which has frequently occurred at 
about the same time as the word, and now, through habit, 
causes the word. It follows that the law of habit is 
adequate to account for the use of words in the absence 
of their objects ; moreover, it would be adequate even 
without introducing images. Although, therefore, images 
seem undeniable, we cannot derive an additional argu- 
ment in their favour from the use of words, which could, 
theoretically, be explained without introducing images. 

When we understand a word, there is a reciprocal 
association between it and the images of what it " means." 
Images may cause us to use words which mean them, and 
these words, heard or read, may in turn cause the appro- 
priate images. Thus speech is a means of producing in 
our hearers the images which are in us. Also, by a teles- 
coped process, words come in time to produce directly 
the effects which would have been produced by the images 
with which they were associated. The general law of 
telescoped processes is that, if A causes B and B causes C, 
it will happen in time that A will cause C directly, without 
the intermediary of B. This is a characteristic of psycho- 
logical and neural causation. In virtue of this law, the 
effects of images upon our actions come to be produced 
by words, even when the words do not call up. appropriate 
images. The more familiar we are with words, the more 
our " thinking " goes on in words instead of images. We 
may, for example, be able to describe a person's appear- 


ance correctly without having at any time had any image 
of him, provided, when we saw him, we ^bought of words 
which fitted him ; the words alone may remain with us 
as a habit, and enable us to speak as if we could recall a 
visual image of the man. In this and other ways the 
understanding of a word often comes to be quite free 
from imagery ; but in first learning the use of language 
it would seem that imagery always plays a very important 

Images as well as words may be said to have " mean- 
ing " ; indeed, the meaning of images seems more primi- 
tive than the meaning of words. What we call (say) an 
image of St. Paul's may be said to " mean " St. Paul's. 
But it is not at all easy to say exactly what constitutes 
the meaning of an image. A memory-image of a particular 
occurrence, when accompanied by a memory-belief, may 
be said to mean the occurrence of which it is an image. 
But most actual images do not have this degree of definite- 
ness. If we call up an image of a dog, we are very likely 
to have a vague image, which is not representative of 
so w ie one special dog, but of dogs in general. When we 
call up an image of a friend's face, we are not likely to 
reproduce the expression he had on some one particular 
occasion, but rather a compromise expression derived from 
many occasions. And there is hardly any limit to the 
vagueness of which images are capable. In such cases, 
the meaning of the image, if defined by relation to the 
prototype, is vague : there is not one definite prototype, 
but a number, none of which is copied exactly. 1 

There is, however, another way of approaching the 
meaning of images, namely through their causal efficacy. 

1 Cf. Semon, Mnemische Empfindungen* chap, xvi, especially 
pp. 301-308. 


What is called an image " of " some definite object, say 
St. Paul's, has some of the effects which the object would 
have. This applies especially to the effects that depend 
upon association. The emotional effects, also, are often 
similar : images may stimulate desire almost as strongly 
as do the objects they represent. And conversely desire 
may cause images x : a hungry man will have images of 
food, and so on. In all these ways the causal laws con- 
cerning images are connected with the causal laws con- 
cerning the objects which the images " mean/ 1 An image 
may thus come to fulfil the function of a general idea. 
The vague image of a dog, which we spoke of a moment 
ago', will have effects which are only connected with dogs 
in general, not the more special effects which would be 
produced by some dogs but not by others. Berkeley and 
Hume, in their attack on general ideas, do not allow for 
the vagueness of images : they assume that every image 
has the definiteness that a physical object would have. 
This is not the case, and a vague image may well have a 
meaning which is general. 

In order to define the " meaning " of an image, we have 
to take account both of its resemblance to one or more 
prototypes, and of its causal efficacy. If there were such 
a thing as a pure imagination-image, without any proto- 
type whatever, it would be destitute of meaning. But 
according to Hume's principle, the simple elements in an 
image, at least, are derived from prototypes except 
possibly in very rare exceptional cases. Often, in such 
instances as our image of a friend's face or of a nondescript 
dog, an image is not derived from one prototype, but from 

1 This phrase is in need of interpretation, as appears from the 
analysis of desire. But the reader can easily supply the inter- 
pretation for himself. 


many ; when this happens, the image is vague, and blurs 
the features in which the various prototypes differ. To 
arrive at the meaning of the image in such a case, we 
observe that there are certain respects, notably associa- 
tions, in which the effects of images resemble those of 
their prototypes. If we find, in a given case, that our 
vague image, say, of a nondescript dog, has those associa- 
tive effects which all dogs would have, but not those 
belonging to any special dog or kind of dog, we may say 
that our image means "dog" in general. If it has all 
the associations appropriate to spaniels but no others, 
we shall say it means " spaniel " ; while if it has all the 
associations appropriate to one particular dog, it will mean 
that dog, however vague it may be as a picture. The 
meaning of an image, according to this analysis, is con- 
stituted by a combination of likeness and associations. 
It is not a sharp or definite conception, and in many 
cases it will be impossible to decide with any certainty 
what an image means. I think this lies in the nature of 
things, and not in defective analysis. 

We, may give somewhat more precision to the above 
account of the meaning of images, and extend it to meaning 
in general. We find sometimes that, in mnemic causation, 
an image or word, as stimulus, has the same effect (or 
very nearly the same effect) as would belong to some 
object, say, a certain dog. In that case we say that the 
image or word means that object. In other cases the 
mnemic effects are not all those of one object, but only 
those shared by objects of a certain kind, e.g. by all dogs. 
In this case the meaning of the image or word is general : 
it means the whole kind. Generality and particularity 
are a matter of degree. If two particulars differ suffi- 
ciently little, their mnemic effects will be the same ; there- 



fore no image or word can mean the one as opposed to 
the other ; this sets a bound to the particularity of mean- 
ing. On the other hand, the mnemic effects of a number 
of sufficiently dissimilar objects will have nothing dis- 
coverable in common ; hence a word which aims at com- 
plete generality, such as " entity " for example, will have 
to be devoid of mnemic effects, and therefore of meaning. 
In practice, this is not the case : such words have verbal 
associations, the learning of which constitutes the study 
of metaphysics. 

The meaning of a word, unlike that of an image, is 
wholly constituted by mnemic causal laws, and not in 
any degree by likeness (except in exceptional cases). 
The word " dog " bears no resemblance to a dog, but its 
effects, like those of an image of a dog, resemble the 
effects of an actual dog in certain respects. It is much 
easier to say definitely what a word means than what 
an image means, since words, however they originated, 
have been framed in later times for the purpose of having 
meaning, and men have been engaged for ages in giving 
increased precision to the meanings of words. But 
although it is easier to say what a word means than what 
an image means, the relation which constitutes meaning 
is much the same in both cases. A word, like an image, 
has the same associations as its meaning has. In addition 
to other associations, it is associated with images of its 
meaning, so that the word tends to call up the image 
and the image tends to call up the word. But this asso- 
ciation is not essential to the intelligent use of words. 
If a word has the right associations with other objects, 
we shall be able to use it correctly, and understand its 
use by others, even if it evokes no image. The theoretical 
understanding of words involves only the power of asso- 


dating them correctly with other words ; the practical 
understanding involves associations with other bodily 

The use of words is, of course, primarily social, for 
the purpose of suggesting to others ideas which we enter- 
tain or at least wish them to entertain. But the aspect 
of words that specially concerns us is their power of 
promoting our own thought. Almost all higher intellectual 
activity is a matter of words, to the nearly total exclusion 
of everything else. The advantages of words for purposes 
of thought are so great that I should never end if I were 
to enumerate them. But a few of them deserve to be 

In the first place, there is no difficulty in producing 
a word, whereas an image cannot always be brought into 
existence at will, and when it comes it often contains 
much irrelevant detail. In the second place, much of our 
thinking is concerned with abstract matters which do not 
readily lend themselves to imagery, and are apt to be 
falsely conceived if we insist upon finding images that 
may be supposed to represent them. The word is always 
concrete and sensible, however abstract its meaning may 
be, and thus by the help of words we are able to dwell on 
abstractions in a way which would otherwise be impossible. 
In the third place, two instances of the same word are 
so similar that neither has associations not capable of 
being shared by the other. Two instances of the word 
" dog " are much more alike than (say) a pug and a great 
dane ; hence the word " dog " makes it much easier to 
think about dogs in general. When a number of objects 
have a common property which is important but not 
obvious, the invention of a name for the common property 
helps us to remember it and to think of the whole set of 


objects that possess it. But it is unnecessary to prolong 
the catalogue of the uses of language in thought. 

At the same time, it is possible to conduct rudimentary 
thought by means of images, and it is important, some- 
times, to check purely verbal thought by reference to 
what it means. In philosophy especially the tyranny of 
traditional words is dangerous, and we have to be on our 
guard against assuming that grammar is the key to meta- 
physics, or that the structure of a sentence corresponds 
at all accurately with the structure of the fact that it 
asserts. Sayce maintained that all European philosophy 
since Aristotle has been dominated by the fact that the 
philosophers spoke Indo-European languages, and there- 
fore supposed the world, like the sentences they were 
used to, necessarily divisible into subjects and predicates. 
When we come to the consideration of truth and falsehood, 
we shall see how necessary it is to avoid assuming too 
close a parallelism between facts and the sentences which 
assert them. Against such errors, the only safeguard is 
to be able, once in a way, to discard words for a moment 
and contemplate facts more directly through images. 
Most serious advances in philosophic thought result from 
some such comparatively direct contemplation of facts. 
But the outcome has to be expressed in words if it is to 
be communicable. Those who have a relatively direct 
vision of facts are often incapable of translating their 
vision into words, while those who possess the words 
have usually lost the vision. It is partly for this reason 
that the highest philosophical capacity is so rare : it 
requires a combination of vision with abstract words 
which is hard to achieve, and too quickly lost in the few 
who have for a moment achieved it. 


IT is said to be one of the merits of the human mind that 
it is capable of framing abstract ideas, and of conducting 
non-sensational thought. In this it is supposed to differ 
from the mind of animals. From Plato onward the " idea " 
has played a great part in the systems of idealizing philo- 
sophers. The " idea " has been, in their hands, always 
something noble and abstract, the apprehension and use 
of which by man confers upon him a quite special dignity. 

The thing we have to consider to-day is this : seeing 
that there certainly are words of which the meaning is 
abstract, and seeing that we can use these words intelli- 
gently, what must be assumed or inferred, or what can be 
discovered by observation, in the way of mental content 
to account for the intelligent use of abstract words ? 

Taken as a problem in logic, the answer is, of course, 
that absolutely nothing in the way of abstract mental 
content is inferable from the mere fact that we can use 
intelligently words of which the meaning is abstract. It 
is clear that a sufficiently ingenious person could manu- 
facture a machine moved by olfactory stimuli which, 
whenever a dog appeared in its neighbourhood, would 
say, " There is a dog/' and when a cat appeared would 
throw stones at it. The act of saying " There is a dog/' 



and the act of throwing stones, would in such a case be 
equally mechanical. Correct speech does not of itself 
afford any better evidence of mental content than the 
performance of any other set of biologically useful move- 
ments, such as those of flight or combat. All that is infer- 
able from language is that two instances of a universal, 
even when they differ very greatly, may cause the utter- 
ance of two instances of the same word which only differ 
very slightly. As we saw in the preceding lecture, the 
word "dog" is useful, partly, because two instances of 
this word are much more similar than (say) a pug and a 
great dane. The use of words is thus a method of sub- 
stituting for two particulars which differ widely, in spite 
of being instances of the same universal, two other par- 
ticulars which differ very little, and which are also instances 
of a universal, namely the name of the previous universal. 
Thus, so far as logic is concerned, we are entirely free to 
adopt any theory as to general ideas which empirical 
observation may recommend. 

Berkeley and Hume made a vigorous onslaught on 
" abstract ideas/' They meant by an idea approxi- 
mately what we should call an image. Locke having 
maintained that he could form an idea of triangle in 
general, without deciding what sort of triangle it was to 
be, Berkeley contended that this was impossible. He 
says : 

" Whether others have this wonderful faculty of 
abstracting their ideas, they best can tell : for myself, I 
dare be confident I have it not. I find, indeed, I have 
indeed a faculty of imagining, or representing to myself, 
the ideas of those particular things I have perceived, and 
of variously compounding and dividing them. I can 
imagine a man with two heads, or the upper parts of a 


man joined to the body of a horse. I can consider the 
hand, the eye, the nose, each by itself abstracted or 
separated from the rest of the body. But, then, whatever 
hand or eye I imagine, it must have some particular 
shape and colour. Likewise the idea of a man that I frame 
to myself must be either of a white, or a black, or a tawny, 
a straight, or a crooked, a tall, or a low, or a middle-sized 
man. I cannot by any effort of thought conceive the 
abstract idea above described. And it is equally impossible 
for me to form the abstract idea of motion distinct from 
the body moving, and which is neither swift nor slow, 
curvilinear nor rectilinear ; and the like may be said of all 
other abstract general ideas whatsoever. To be plain, I own 
myself able to abstract in one sense, as when I consider 
some particular parts of qualities separated from others, 
with which, though they are united in some object, yet 
it is possible they may really exist without them. But 
I deny that I can abstract from one another, or con- 
ceive separately, those qualities which it is impossible 
should exist so separated ; or that I can frame a general 
notion, by abstracting from particulars in the manner 
aforesaid which last are the two proper acceptations of 
abstraction. And there is ground to think most men will 
acknowledge themselves to be in my case. The generality 
of men which are simple and illiterate never pretend to 
abstract notions. It is said they are difficult and not 
to be attained without pains and study ; we may there- 
fore reasonably conclude that, if such there be, they are 
confined only to the learned. 

" I proceed to examine what can be alleged in defence 
of the doctrine of abstraction, and try if I can discover 
what it is that inclines the men of speculation to embrace 
an opinion so remote from common sense as that seems 


to be. There has been a late excellent and deservedly 
esteemed philosopher who, no doubt, has given it very 
much countenance, by seeming to think the having abstract 
general ideas is what puts the widest difference in point 
of understanding betwixt man and beast. ' The having 
of general ideas/ saith he, ' is that which puts a perfect 
distinction betwixt man and brutes, and is an excellency 
which the faculties of brutes do by no means attain unto. 
For, it is evident we observe no footsteps in them of making 
use of general signs for universal ideas ; from which we 
have reason to imagine that they have not the faculty 
of abstracting, or making general ideas, since they have 
no use of words or any other general signs/ And a little 
after : ' Therefore, I think, we may suppose that it is 
in this that the species of brutes are discriminated from 
men, and it is that proper difference wherein they are 
wholly separated, and which at last widens to so wide a 
distance. For, if they have any ideas at all, and are not 
bare machines (as some would have them), we cannot 
deny them to have some reason. It seems as evident to 
me that they do, some of them, in certain instances reason 
as that they have sense; but it is only in particular 
ideas, just as they receive them from their senses. They 
are the best of them tied up within those narrow bounds, 
and have not (as I think) the faculty to enlarge them by 
any kind of abstraction/ (Essay on Human Understanding, 
Bk. II, chap, xi, paragraphs 10 and n.) I readily agree 
with this learned author, that the faculties of brutes can 
by no means attain to abstraction. But, then, if this be 
made the distinguishing property of that sort of animals, 
I fear a great many of those that pass for men must be 
reckoned into their number. The reason that is here 
assigned why we have no grounds to think brutes have 


abstract general ideas is, that we observe in them no use 
of words or any other general signs ; which is built on 
this supposition that the making use of words implies 
the having general ideas. From which it follows that men 
who use language are able to abstract or generalize their 
ideas. That this is the sense and arguing of the author 
will further appear by his answering the question he in 
another place puts : ' Since all things that exist are only 
particulars, how come we by general terms ? ' His answer 
is : ' Words become general by being made the signs of 
general ideas. 1 (Essay on Human Understanding, Bk. Ill, 
chap, iii, paragraph 6.) But it seems that a word becomes 
general by being made the sign, not of an abstract general 
idea, but of several particular ideas, any one of which it 
indifferently suggests to the mind. For example, when it 
is said ' the change of motion is proportional to the im- 
pressed force/ or that ' whatever has extension is divisible/ 
these propositions are to be understood of motion and 
extension in general ; and nevertheless it will not follow 
that they suggest to my thoughts an idea of motion 
without a body moved, or any determinate direction and 
velocity, or that I must conceive an abstract general idea 
of extension, which is neither line, surface, nor solid, 
neither great nor small, black, white, nor red, nor of any 
other determinate colour. It is only implied that what- 
ever particular motion I consider, whether it be swift or 
slow, perpendicular, horizontal, or oblique, or in whatever 
object, the axiom concerning it holds equally true. As 
does the other of every particular extension, it matters 
not whether line, surface, or solid, whether of this or 
that magnitude or figure. 

" By observing how ideas become general, we may the 
better judge how words are made so. And here it is to be 


noted that I do not deny absolutely there are general 
ideas, but only that there are any abstract general ideas ; 
for, in the passages we have quoted wherein there is men- 
tion of general ideas, it is always supposed that they are 
formed by abstraction, after the manner set forth in sec- 
tions 8 and 9. Now, if we will annex a meaning to our 
words, and speak only of what we can conceive, I believe 
we shall acknowledge that an idea which, considered in 
itself, is particular, becomes general by being made to 
represent or stand for all other particular ideas of the same 
sort. To make this plain by an example, suppose a 
geometrician is demonstrating the method of cutting a 
line in two equal parts. He draws, for instance, a black 
line of an inch in length : this, which in itself is a particular 
line, is nevertheless with regard to its signification general, 
since, as it is there used, it represents all particular lines 
whatsoever ; so that what is demonstrated of it is demon- 
strated of all lines, or, in other words, of a line in general. 
And, as that particular line becomes general by being 
made a sign, so the name ' line/ which taken absolutely 
is particular, by being a sign is made general. And as 
the former owes its generality not to its being the sign of 
an abstract or general line, but of all particular right lines 
that may possibly exist, so the latter must be thought to 
derive its generality from the same cause, namely, the 
various particular lines which it indifferently denotes." * 
Berkeley's view in the above passage, which is essen- 
tially the same as Hume's, does not wholly agree with 
modern psychology, although it comes nearer to agree- 
ment than does the view of those who believe that there 

are ift the mind single contents which can be called abstract 


1 Introduction to A Treatise concerning the Principle* of Human 
Knowledge, paragraphs 10, n, and 12. 


ideas. The way in which Berkeley's view is inadequate 
is chiefly in the fact that images are as a rule not of one 
definite prototype, but of a number of related similar 
prototypes. On this subject Semon has written well. In 
Die Mneme, pp. 217 ff., discussing the effect of repeated 
similar stimuli in producing and modifying our images, 
he says : " We choose a case of mnemic excitement 
whose existence we can perceive for ourselves by intro- 
spection, and seek to ekphore the bodily picture of our 
nearest relation in his absence, and have thus a pure 
mnemic excitement before us. At first it may seem to 
us that a determinate quite concrete picture becomes 
manifest in us, but just when we are concerned with a 
person with whom we are in constant contact, we shall find 
that the ekphored picture has something so to speak 
generalized. It is something like those American photo- 
graphs which seek to display what is general about a type 
by combining a great number of photographs of different 
heads over each other on one plate. In our opinion, the 
generalizations happen by the homophonic working of 
different pictures of the same face which we have come 
across in the most different conditions and situations, 
once pale, once reddened, once cheerful, once earnest, 
once in this light, and once in that. As soon as we do 
not let the whole series of repetitions resound in us uni- 
formly, but give our attention to one particular moment 
out of the many . . . this particular mnemic stimulus at 
once overbalances its simultaneously roused predecessors 
and successors, and we perceive the face in question 
with concrete definiteness in that particular situation." 
A little later he says : " The result is at least in man, 
but probably also in the higher animals the develop- 
ment of a sort of physiological abstraction. Mnemic 


homophony gives us, without the addition of other pro- 
cesses of thought, a picture of our friend X which is in 
a certain sense abstract, not the concrete in any one 
situation, but X cut loose from any particular point of 
time. If the circle of ekphored engrams is drawn even 
more widely, abstract pictures of a higher order appear : 
for instance, a white man or a negro. In my opinion, 
the first form of abstract concepts in general is based 
upon such abstract pictures. The physiological abstrac- 
tion which takes place in the above described manner is 
a predecessor of purely logical abstraction. It is by no 
means a monopoly of the human race, but shows itself 
in various ways also among the more highly organized 
animals/' The same subject is treated in more detail 
in Chapter xvi of Die mnemischen Empfindungen, but 
what is said there adds nothing vital to what is contained 
in the above quotations. 

It is necessary, however, to distinguish between the 
vague and the general. So long as we are content with 
Semon's composite image, we may get no farther than 
the vague. The question whether this image takes us 
to the general or not depends, I think, upon the question 
whether, in addition to the generalized image, we have 
also particular images of some of the instances out of 
which it is compounded. Suppose, for example, that on 
a number of occasions you had seen one negro, and that 
you did not know whether this one was the same or 
different on the different occasions. Suppose that in the 
end you had an abstract memory-image of the different 
appearances piesented by the negro on different occasions, 
but no memory-image of any one of the single appear- 
ances. In that case your image would be vague. If, 
on the other hand, you have, in addition to the general- 


ized image, particular images of the several appearances, 
sufficiently clear to be recognized as different, and as 
instances of the generalized picture, you will then not 
feel the generalized picture to be adequate to any one 
particular appearance, and you will be able to make it 
function as a general idea rather than a vague idea. If 
this view is correct, no new general content needs to be 
added to the generalized image. What needs to be 
added is particular images compared and contrasted 
with the generalized image. So far as I can judge by 
introspection, this does occur in practice. Take for 
example Semon's instance of a friend's face. Unless we 
make some special effort of recollection, the face is likely 
to come before us with an average expression, very blurred 
and vague, but we can at will recall how our friend looked 
on some special occasion when he was pleased or angry 
or unhappy, and this enables us to realize the generalized 
character of the vague image. 

There is, however, another way of distinguishing 
between the vague, the particular and the general, and 
this is -not by their content, but by the reaction which 
they produce. A word, for example, may be said to be 
vague when it is applicable to a number of different 
individuals, but to each as individuals ; the name Smith, 
for example, is vague : it is always meant to apply to one 
man, but there are many men to each of whom it applies. 1 
The word " man/' on the other hand, is general. We say, 
" This is Smith/' but we do not say " This is man/' but 
" This is a man." Thus we may say that a word embodies 
a vague idea when its effects are appropriate to an indi- 

1 " Smith " would only be a quite satisfactory representation 
of vague words if we failed to discriminate between different people 
called Smith. 


vidual, but are the same for various similar individuals, 
while a word embodies a general idea when its effects are 
different from those appropriate to individuals. In what 
this difference consists it is, however, not easy to say. 
I am inclined to think that it consists merely in the know- 
ledge that no one individual is represented, so that what 
distinguishes a general idea from a vague idea is merely 
the presence of a certain accompanying belief. If this 
view is correct, a general idea differs from a vague one 
in a way analogous to that in which a memory-image 
differs from an imagination-image. There also we found 
that the difference consists merely of the fact that a 
memory-image is accompanied by a belief, in this case as 
to the past. 

It should also be said that our images even of quite 
particular occurrences have always a greater or a less 
degree of vagueness. That is to say, the occurrence 
might have varied within certain limits without causing 
our image to vary recognizably. To arrive at the general 
it is necessary that we should be able to contrast it with 
a number of relatively precise images or words for par- 
ticular occurrences ; so long as ail our images and words 
are vague, we cannot arrive at the contrast by which 
the general is defined. This is the justification for the 
view which I quoted on p. 184 from Ribot (op. cit., p. 32), 
viz. that intelligence progresses from the indefinite to the 
definite, and that the vague appears earlier than either 
the particular or the general. 

I think the view which I have been advocating, to the 
effect that a general idea is distinguished from a vague 
one by the presence of a judgment, is also that intended 
by Ribot when he says (op. cit., p. 92) : " The generic 
image is never, the concept is always, a judgment* We 


know that for logicians (formerly at any rate) the con- 
cept is the simple and primitive element ; next comes the 
judgment, uniting two or several concepts ; then ratio- 
cination, combining two or several judgments. For the 
psychologists, on the contrary, affirmation is the funda- 
mental act ; the concept is the result of judgment (explicit 
or implicit), of similarities with exclusion of differences." 

A great deal of work professing to be experimental has 
been done in recent years on the psychology of thought. 
A good summary of such work up to the year 1909 is 
contained in Titchener's Lectures on the Experimental 
Psychology of the Thought Processes (1909). Three articles 
in the Archiv fur die gesammte Psychologie by Watt, 1 
Messer 2 and Biihler 3 contain a great deal of the material 
amassed by the methods which Titchener calls experi- 

For my part I am unable to attach as much import- 
ance to this work as many psychologists do. The method 
employed appears to me hardly to fulfil the conditions of 
scientific experiment. Broadly speaking, what is done is, 
that a set of questions are asked of various people, their 
answers are recorded, and likewise their own accounts, 
based upon introspection, of the- processes of thought 
which led them to give those answers. Much too much 
reliance seems to me to be placed upon the correctness 
of their introspection. On introspection as a method I 
have spoken earlier (Lecture VI). I am not prepared, 
like Professor Watson, to reject it wholly, but I do con- 
sider that it is exceedingly fallible and quite peculiarly 

1 Henry J. Watt, Experimentelle Beitrdge zu ciner Theorie des 
Denkens t vol. iv (1905), pp. 289-436. 

August Messer, Expcrimentell-psychologische Untersuchuvgen 
Uber das Denken, vol. iii (1906), pp. 1-224. 

3 Karl Biihler, Uber Gedanken, vol. ix (1907), pp. 297-365. 


liable to falsification in accordance with preconceived 
theory. It is like depending upon the report of a short- 
sighted person as to whom he sees coming along the 
road at a moment when he is firmly convinced that Jones 
is sure to come. If everybody were short-sighted and 
obsessed with beliefs as to what was going to be visible, 
we might have to make the best of such testimony, but 
we should need to correct its errors by taking care to 
collect the simultaneous evidence of people with the most 
divergent expectations. There is no evidence that this 
was done in the experiments in question, nor indeed that 
the influence of theory in falsifying the introspection was 
at all adequately recognized. I feel convinced that if 
Professor Watson had been one of the subjects of the 
questionnaires, he would have given answers totally 
different from those recorded in the articles in question. 
Titchener quotes an opinion of Wundt on these investiga- 
tions, which appears to me thoroughly justified. " These 
experiments/' he says, " are not experiments at all in 
the sense of a scientific methodology ; they are counter- 
feit experiments, that seem methodical simply because 
they are ordinarily performed in a psychological labora- 
tory, and involve the co-operation of two persons, who 
purport to be experimenter and observer. In reality, 
they are as unmethodical as possible ; they possess none 
of the special features by which we distinguish ( the intro- 
spections of experimental psychology from the casual 
introspections of everyday life." J Titchener, of course, 
dissents from this opinion, but I cannot see that his 
reasons for dissent are adequate. My doubts are only 
increased by the fact that Biihler at any rate used trained 
psychologists as his subjects. A trained psychologist is, 
Titchener, op. cit. t p. 79. 


of course, supposed to have acquired the habit of observa- 
tion, but he is at least equally likely to have acquired 
a habit of seeing what his theories require. We may 
take Biihler's Uber Gedankcn to illustrate the kind of 
results arrived at by such methods. Biihler says (p. 303) : 
" We ask ourselves the general question : ' What do 
we experience when we think ? ' Then we do not at all 
attempt a preliminary determination of the concept 
' thought/ but choose for analysis only such processes as 
everyone would describe as processes of thought." The 
most important thing in thinking, he says, is " awareness 
that ..." (Bewusstheit dass), which he calls a thought. 
It is, he says, thoughts in this sense that are essential 
to thinking. Thinking, he maintains, does not need 
language or sensuous presentations. " I assert rather 
that in principle every object can be thought (meant) 
distinctly, without any help from sensuous presentation 
(Anschauungshilferi). Every individual shade of blue 
colour on the picture that hangs in my room I can think 
with complete distinctness unsensuously (unanschaulich) , 
provided it is possible that the object should be given to 
me in another manner than by the help of sensations. 
How that is possible we shall see later." What he calls 
a thought (Gedanke) cannot be reduced, according to 
him, to other psychic occurrences. He maintains that 
thoughts consist for the most part of known rules (p. 342). 
It is clearly essential to the interest of this theory that 
the thought or rule alluded to by Biihler should not need 
to be expressed in words, for if it is expressed in words it 
is immediately capable of being dealt with on the lines 
with which the behaviourists have familiarized us. It is 
clear also that the supposed absence of words rests solely 
upon the introspective testimony of the persons experi- 


mented upon. I cannot think that there is sufficient 
certainty of their reliability in this negative observation 
to make us accept a difficult and revolutionary view of 
thought, merely because they have failed to observe the 
presence of words or their equivalent in their thinking. 
I think it far more likely, especially in view of the fact 
that the persons concerned were highly educated, that we 
are concerned with telescoped processes, in which habit 
has caused a great many intermediate terms to be elided 
or to be passed over so quickly as to escape observation. 
I am inclined to think that similar remarks apply to 
the general idea of " imageless thinking/' concerning 
which 'there has been much controversy. The advocates 
of imageless thinking are not contending merely that there 
can be thinking which is purely verbal ; they are con- 
tending that there can be thinking which proceeds neither 
in words nor in images. My own feeling is that they 
have rashly assumed the presence of thinking in cases 
where habit has rendered thinking unnecessary. When 
Thorndike experimented with animals in cages, he found 
that the associations established were between a sensory 
stimulus and a bodily movement (not the idea of it), 
without the need of supposing any non-physiological 
intermediary (op. cit., p. 100 ft.). The same thing, it 
seems to me, applies to ourselves. A certain sensory 
situation produces in us a certain bodily movement. 
Sometimes' this movement consists in uttering \tords. 
Prejudice leads us to suppose that between the sensory 
stimulus and the utterance of the words a process 
of thought must have intervened, but there seems 
no good reason for such a supposition. Any habitual 
action, such as eating or dressing, may be performed on 
the appropriate occasion, without any need of thought, 


and the same seems to be true of a painfully large pro- 
portion of our talk. What applies to uttered speech 
applies of course equally to the internal speech which is 
not uttered. I remain, therefore, entirely unconvinced 
that there is any such phenomenon as thinking which 
consists neither of images nor of words, or that " ideas " 
have to be added to sensations and images as part of the 
material out of which mental phenomena are built. 

The question of the nature of our consciousness of the 
universal is much affected by our view as to the general 
nature of the relation of consciousness to its object. If we 
adopt the view of Brentano, according to which all mental 
content has essential reference to an object, it is then 
natural to suppose that there is some peculiar kind of 
mental content of which the object is a universal, as 
oppose to a particular. According to this view, a par- 
ticular cat can be ^>m:eived or imagined, while the universal 
" cat " is conceived. But this whole manner of viewing 
our dealings with universals has to be abandoned when 
the relation of a mental occurrence to its " object " is 
regarded as merely indirect and causal, which is the view 
that we have adopted. The mental content is, of course, 
always particular, and the question as to what it " means " 
(in case it means anything) is one which cannot be settled 
by merely examining the intrinsic character of the mental 
content, but only by knowing its causal connections in 
the case of the person concerned. To say that a certain 
thought " means " a universal as opposed to either a vague 
or a particular, is to say something exceedingly complex. 
A horse will behave in a certain manner whenever he smells 
a bear, even if the smell is derived from a bearskin. That 
is to say, any environment containing an instance of the 
universal " smelL of a bear " produces closely similar 


behaviour in the horse, but we do not say that the horse 
is conscious of this universal. There is equally little reason 
to regard a man as conscious of the same universal, 
because under the same circumstances he can react by 
saying, " I smell a bear." This reaction, like that of the 
horse, is merely closely similar on different occasions 
where the environment affords instances of the same uni- 
versal. Words of which the logical meaning is universal 
can therefore be employed correctly, without anything 
that could be called consciousness of universals. Such 
consciousness in the only sense in which it can be said to 
exist is a matter of reflective judgment consisting in the 
observation of similarities and differences. A universal 
never appears before the mind as a single object in the sort 
of way in which something perceived appears. I think 
a logical argument could be produced to show that uni- 
versals are part of the structure of the world, but they 
are an inferred part, not a part of our data. What exists 
in us consists of various factors, some open to external 
observation, others only visible to introspection. The 
factors open to external observation are primarily habits, 
having the peculiarity that very similar reactions are 
produced by stimuli which are in many respects very 
different from each other. Of this the reaction of the 
horse to the smell of the bear is an instance, and so is the 
reaction of the man who says " bear " under the same 
circumstances. The verbal reaction is, of course, the most 
important from the point of view of what may be called 
knowledge of universals. A man who can always use the 
word " dog " when he sees a dog may be said, in a certain 
sense, to know the meaning of the word " dog," and in 
that sense to have knowledge of the universal " dog." 
But there is, of course, a further stage reached by the 


logician in which he not merely reacts with the word 
" dog," but sets to work to discover what it is in the 
environment that causes in him this almost identical 
reaction on different occasions. This further stage con- 
sists in knowledge of similarities and differences : simi- 
larities which are necessary to the applicability of the 
word " dog/' and differences which are compatible with 
it. Our knowledge of these similarities and differences is 
never exhaustive, and therefore our knowledge of the 
meaning of a universal is never complete. 

In addition to external observable habits (including the 
habit of words), there is also the generic image produced 
by the superposition, or, in Semon's phrase, homophony, 
of a number of similar perceptions. This image is vague 
so long as the multiplicity of its prototypes is not recog- 
nized, but becomes universal when it exists alongside of 
the more specific images of its instances, and is knowingly 
contrasted with them. In this case we find again, as we 
found when we were discussing words in general in the 
preceding lecture, that images are not logically necessary 
in order to account for observable behaviour, i.e. in this 
case intelligent speech. Intelligent speech could exist as a 
motor habit, without any accompaniment of images, and 
this conclusion applies to words of which the meaning is 
universal, just as much as to words of which the mean- 
ing is relatively particular. If this conclusion is valid, 
it follows that behaviourist psychology, which eschews 
introspective data, is capable of being an independent 
science, and of accounting for all that part of the behaviour 
of other people which is commonly regarded as evidence 
that they think. It must be admitted that this conclusion 
considerably weakens the reliance which can be placed 
upon introspective data. They must be accepted simply 


on account of the fact that we seem to perceive them, 
not on account of their supposed necessity for explaining 
the data of external observation. 

This, at any rate, is the conclusion to which we are 
forced, so long as, with the behaviourists, we accept 
common-sense views of the physical world. But if, as 
I have urged, the physical world itself, as known, is in- 
fected through and through with subjectivity, if, as the 
theory of relativity suggests, the physical universe contains 
the diversity of points of view which we have been accus- 
tomed to regard as distinctively psychological, then we 
are brought back by this different road to the necessity 
for trusting observations which are in an important sense 
private. And it is the privacy of introspective data which 
causes much of the behaviourists' objection to them. 

This is, an example of the difficulty of constructing an 
adequate philosophy of any one science without taking 
account of other sciences. The behaviourist philosophy 
of psychology, though in many respects admirable from 
the point of view of method, appears to me to fail in the 
last analysis because it is based upon an inadequate 
philosophy of physics. In spite, therefore, of the fact 
that the evidence for images, whether generic or par- 
ticular, is merely introspective, I cannot admit that 
images should be rejected, or that we should minimize 
their function in our knowledge of what is remote in time 
or space. 


BELIEF, which is our subject to-day, is the central 
problem in the analysis of mind. Believing seems the 
most " mental " thing we do, the thing most remote 
from what is done by mere matter. The whole intel- 
lectual life consists of beliefs, and of the passage from 
one belief to another by what is called " reasoning." 
Beliefs give knowledge and error ; they are the vehicles 
of truth and falsehood. Psychology, theory of know- 
ledge and metaphysics revolve about belief, and on the 
view we take of belief our philosophical outlook largely 

Before embarking upon the detailed analysis of belief, 
we shall do well to note certain requisites which any 
theory must fulfil. 

(i) Just as words are characterized by meaning, so 
beliefs are characterized by truth or falsehood. And 
just as meaning consists in relation to the object meant, 
so truth and falsehood consist in relation to something 
that lies outside the belief. You may believe that such- 
and-such a horse will win the Derby. The time comes, 
and your horse wins or does not win ; according to the 
outcome, your belief was true or false. You may believe 
that six times nine is fifty-six ; in this case also there 



is a fact which makes your belief false. You may believe 
that America was discovered in 1492, or that it was 
discovered in 1066. In the one case your belief is true, 
in the other false ; in either case its truth or falsehood 
depends upon the actions of Columbus, not upon any- 
thing present or under your control. What makes a 
belief 'true or false I call a " fact." The particular fact 
that makes a given belief true or false I call its " ob- 
jective," I and the relation of the belief to its objective 
I call the " reference " or the " objective reference " of 
the belief. Thus, if I believe that Columbus crossed the 
Atlantic in 1492, the " objective " of my belief is Colum- 
bus's actual voyage, and the " reference " of my belief 
is the relation between my belief and the voyage that 
relation, namely, in virtue of which the voyage makes 
my belief true (or, in another case, false). " Reference " 
of beliefs differs from " meaning " of words in various 
ways, but especially in the fact that it is of two kinds, 
" true " reference and " false " reference. The truth or 
falsehood of a belief does not depend upon anything 
intrinsic to the belief, but upon the nature of its relation 
to its objective. The intrinsic nature of belief can be 
treated without reference to what makes it true or false. 
In the remainder of the present lecture I shall ignore 
truth and falsehood, which will be the subject of Lecture 
XIII. It is the intrinsic nature of belief that will concern 
us to-day. 

(2) We must distinguish between believing and what 
is believed. I may believe that Columbus crossed the 
Atlantic, that all Cretans are liars, that two and two 
are four, or that nine times six is fifty-six ; in all these 

This terminology is suggested by Meinong, but is not exactly 
the same as his. 


cases the believing is just the same, and only the contents 
believed are different. I may remember my breakfast 
this morning, my lecture last week, or my first sight of 
New York. In all these cases the feeling of memory- 
belief is just the same, and only what is remembered 
differs. Exactly similar remarks apply to expectations. 
Bare assent, memory and expectation are forms of belief ; 
all three are different from what is believed, and each 
has a constant character which is independent of what 
is believed. 

In Lecture I we criticized the analysis of a presentation 
into act, content and object. But our analysis of belief 
contains three very similar elements, namely the believing, 
what is believed and the objective. The objections to 
the act (in the case of presentations) are not valid against 
the believing in the case of beliefs, because the believing 
is an actual experienced feeling, not something postulated, 
like the act. But it is necessary first to complete our 
preliminary requisites, and then to examine the content 
of a belief. After that, we shall be in a position to return 
to the question as to what constitutes believing. 

(3) What is believed, and the believing, must both 
consist of present occurrences in the believer, no matter 
what may be the objective of the belief. Suppose I believe, 
for example, "that Caesar crossed the Rubicon. 1 ' The 
objective of my belief is an event which happened long 
ago, which I never saw and do not remember. This event 
itself is not in my mind when I believe that it happened. 
It is not correct to say that I am believing the actual 
event ; what I am believing is something now in my 
mind, something related to the event (in a way which 
we shall investigate in Lecture XIII), but obviously not 
to be confounded with the event, since the event is not 


occurring now but the believing is. What a man is 
believing at a given moment is wholly determinate if 
we know the contents of his mind at that moment ; but 
Caesar's crossing of the Rubicon was an historical physical 
event, which is distinct from the present contents of every 
present mind. What is believed, however true it may 
be, is not the actual fact that makes the belief true, but 
a present event related to the fact. This present event, 
which is what is believed, I shall call the " content " 
of the belief. We have already had occasion to notice 
the distinction between content and objective in the 
case of memory-beliefs, where the content is " this oc- 
curred-" and the objective is the past event. 

(4) Between content and objective there is sometimes 
a very wide gulf, for example in the case of " Caesar 
crossed the Rubicon." This gulf may, when it is first 
perceived, give us a feeling that we cannot really " know " 
anything about the outer world. All we can " know," 
it may be said, is what is now in our thoughts. If Caesar 
and the Rubicon cannot be bodily in our thoughts, it 
might seem as though we must remain cut off from 
knowledge of them. I shall not now deal at length with 
this feeling, since it is necessary first to define " know- 
ing," which cannot be done yet. But I will say, as a 
preliminary answer, that the feeling assumes an ideal 
of knowing which I believe to be quite mistaken : it 
assumes, if it is thought out, something like the mystic 
unity of knower and known. These two are often said 
to be combined into a unity by the fact of cognition ; 
hence when this unity is plainly absent, it may seem as 
if there were no genuine cognition. For my part, I think 
such theories and feelings wholly mistaken : I believe 
knowing to be a very external and complicated relation, 


incapable of exact definition, dependent upon causal 
laws, and involving no more unity than there is between 
a signpost and the town to which it points. I shall return 
to this question on a later occasion ; for the moment these 
provisional remarks must suffice. 

(5) The objective reference of a belief is connected 
with the fact that all or some of the constituents of its 
content have meaning. If I say " Caesar conquered 
Gaul/' a person who knows the meaning of the three 
words composing my statement knows as much as can 
be known about the nature of the objective which would 
make my statement true. It is clear that the objective 
reference of a belief is, in general, in some way derivative 
from the meanings of the words or images that occur 
in its content. There are, however, certain complications 
which must be borne in mind. In the first place, it 
might be contended that a memory-image acquires mean- 
ing only through the memory-belief, which would seem, 
at least in the case of memory, to make belief more 
primitive than the meaning of images. In the second 
place, it is a very singular thing that meaning, which 
is single, should generate objective reference, which is 
dual, namely true and false. This is one of the facts 
which any theory of belief must explain if it is to be 

It is now time to leave these preliminary requisites, 
and attempt the analysis of the contents of beliefs. 

The first thing to notice about what is believed, i.e. 
about the content of a belief, is that it is always complex. 
We believe that a certain thing has a certain property, 
or a certain relation to something else, or that it oc- 
curred or will occur (in the sense discussed at the end of 
Lecture IX) ; or we may believe that all the members of 


a certain class have a certain property, or that a certain 
property sometimes occurs among the members of a class ; 
or we may believe that if one thing happens, another will 
happen (for example, " if it rains I shall bring my um- 
brella "), or we may believe that something does not 
happen, or did not or will not happen (for example, " it 
won't rain ") ; or that one of two things must happen 
(for example, " either you withdraw your accusation, or 
I shall bring a libel action "). The catalogue of the sorts 
of things we may believe is infinite, but all of them are 

Language sometimes conceals the complexity of a 
belief.. We say that a person believes in God, and it 
might seem as if God formed the whole content of the 
belief. But what is really believed is that God exists, 
which is very far from being simple. Similarly, when a 
person has a memory-image with a memory-belief, the 
belief is " this occurred/' in the sense explained in 
Lecture IX ; and " this occurred " is not simple. In 
like manner all cases where the content of a belief seems 
simple at first sight will be found, on examination, to 
confirm the view that the content is always complex. 

The content of a belief involves not merely a plurality 
of constituents, but definite relations between them ; it 
is not determinate when its constituents alone are given. 
For example, " Plato preceded Aristotle " and " Aristotle 
preceded Plato " are both contents which may be believed, 
but, although they consist of exactly the same constituents, 
they are different, and even incompatible. 

The content of a belief may consist of words only, or 
of images only, or of a mixture of the two, or of either 
or both together with one or more sensations. It must 
contain at least one constituent which is a word or an 


image, and it may or may not contain one or more sensa- 
tions as constituents. Some examples will make these 
various possibilities clear. 

We may take first recognition, in either of the forms 
" this is of such-and-such a kind " or " this has occurred 
before." In either case, present sensation is a constituent. 
For example, you hear a noise, and you say to yourself 
"tram/' Here the noise and the word "tram" are 
both constituents of your belief ; there is also a relation 
between them, expressed by " is " in the proposition 
" that is a tram." As soon as your act of recognition 
is completed by the occurrence of the word " tram," 
your actions are affected : you hurry if you want the tram, 
or cease to hurry if you want a bus. In this case the 
content of your belief is a sensation (the noise) and a 
word (" tram ") related in a way which may be called 

The same noise may bring into your mind the visual 
image of a tram, instead of the word " tram." In this 
case your belief consists of a sensation and an image 
suitable related. Beliefs of this class are what are called 
" judgments of perception." As we saw in Lecture VIII, 
the images associated with a sensation often come with 
such spontaneity and force that the unsophisticated do 
not distinguish them from the sensation ; it is only the 
psychologist or the skilled observer who is aware of the 
large mnemic element that is added to sensation to make 
perception. It may be objected that what is added 
consists merely of images without belief. This is no 
doubt sometimes the case, but is certainly sometimes 
not the case. That belief always occurs in perception 
as opposed to sensation it is not necessary for us to 
maintain ; it is enough for our purposes to note that it 


sometimes occurs, and that when it does, the content 
of our belief consists of a sensation and an image suitably 

In a pure memory-belief only images occur. But a 
mixture of words and images is very common in memory. 
You have an image of the past occurrence, and you say 
to yourself: " Yes, that's how it was." Here the image 
and the words together make up the content of the 
belief. And when the remembering of an incident has 
become a habit, it may be purely verbal, and the memory- 
belief may consist of words alone. 

The more complicated forms of belief tend to consist 
only of words. Often images of various kinds accompany 
them, but they are apt to be irrelevant, and to form no 
part of what is actually believed. For example, in think- 
ing of the Solar System, you are likely to have vague 
images of pictures you have seen of the earth surrounded 
by clouds, Saturn and his rings, the sun during an eclipse, 
and so on ; but none of these form part of your belief 
that the planets revolve round the sun in elliptical orbits. 
The only images that form an actual part of such beliefs 
are, as a rule, images of words. And images of words, 
for the reasons considered in Lecture VIII, cannot be 
distinguished with any certainty from sensations, when, 
as is often, if not usually, the case, they are kinaesthetic 
images of pronouncing the words. 

It is impossible for a belief to consist of sensations 
alone, except when, as in the case of words, the sensations 
have associations which make them signs possessed of 
meaning. The reason is that objective reference is of 
the essence of belief, and objective reference is derived 
from meaning. When I speak of a belief consisting 
partly of sensations and partly of words, I do not mean 


to deny that the words, when they are not mere images, 
are sensational, but that they occur as signs, not (so to 
speak) in their own right. To revert to the noise of the 
tram, when you hear it and say " tram," the noise and 
the word are both sensations (if you actually pronounce 
the word), but the noise is part of the fact which makes 
your belief true, whereas the word is not part of this 
fact. It is the meaning of the word "tram," not the 
actual word, that forms part of the fact which is the 
objective of your belief. Thus the word occurs in the 
belief as a symbol, in virtue of its meaning, whereas 
the noise enters into both the belief and its objective. 
It is this that distinguishes the occurrence of words as 
symbols from the occurrence of sensations in their own 
right : the objective contains the sensations that occur 
in their own right, but contains only the meanings of 
the words that occur as s}7mbols. 

For the sake of simplicity, we may ignore the cases 
in which sensations in their own .right form part of the 
content of a belief, and confine ourselves to images and 
words. We may also omit the cases in which both images 
and words occur in the content of a belief. Thus we 
become confined to two cases : (a) when the content 
consists wholly of images, (b) when it consists wholly 
of words. The case of mixed images and words has no 
special importance, and its omission will do no harm. 

Let us take in illustration a case of memory. Suppose 
you are thinking of some familiar room. You may call 
up an image of it, and in your image the window may 
be to the left of the door. Without any intrusion of 
words, you may believe in the correctness of your image. 
You then have a belief, consisting wholly of images, 
which becomes, when put into words, " the window is 


to the left of the door." You may yourself use these 
words and proceed to believe them. You thus pass 
from an image-content to the corresponding word-content. 
The content is different in the two cases, but its objective 
reference is the same. This shows the relation of image- 
beliefs to word-beliefs in a very simple case. In more 
elaborate cases the relation becomes much less simple. 

It may be said that even in this very simple case the 
objective reference of the word-content is not quite the 
same as that of the image-content, that images have a 
wealth of concrete features which are lost when words 
are substituted, that the window in the image is not a 
mere window in the abstract, but a window of a certain 
shape and size, not merely to the left of the door, but 
a certain distance to the left, and so on. In reply, it 
may be admitted at once that there is, as a Yule, a certain 
amount of truth in the objection. But two points may 
be urged to minimize its force. First, images do not, 
as a rule, have that wealth of concrete detail that would 
make it impossible to express them fully in words. They 
are vague and fragmentary : a finite number of words, 
though perhaps a large number, would exhaust at least 
their significant features. For and this is our second 
point images enter into the content of a belief through 
the fact that they are capable of meaning, and their 
meaning does not, as a rule, have as much complexity 
as they have : some of their characteristics are usually 
devoid of meaning. Thus it may well be possible to ex- 
tract in words all that has meaning in an image-content ; 
in that case the word-content and the image-content will 
have exactly the same objective reference. 

The content of a belief, when expressed in words, is 
the same thing (or very nearly the same thing) as what in 


logic is called a " proposition." A proposition is a series 
of words (or sometimes a single word) expressing the 
kind of thing that can be asserted or denied. " That all 
men are mortal," " that Columbus discovered America," 
" that Charles I died in his bed," " that all philosophers 
are wise," are propositions. Not any series of words is 
a proposition, but only such series of words as have 
" meaning/* or, in our phraseology, " objective reference." 
Given the meanings of separate words, and the rules of 
syntax, the meaning of a proposition is determinate. 
This is the reason why we can understand a sentence 
we never heard before. You probably never heard 
before the proposition " that the inhabitants of the 
Andaman Islands habitually eat stewed hippopotamus 
for dinner," but there is no difficulty in understanding 
the proposition. The question of the relation between 
the meaning of a sentence and the meanings of the 
separate words is difficult, and I shall not pursue it now ; 
I brought it up solely as being illustrative of the nature 
of propositions. 

We may extend the term " proposition " so as to cover 
the image-contents of beliefs consisting of images. Thus, 
in the case of remembering a room in which the window 
is to the left of the door, when we believe the image- 
content the proposition will consist of the image of the 
window on the left together with the image of the door 
on the right. We will distinguish propositions of this 
kind as " image-propositions " and propositions in words 
as " word-propositions." We may identify propositions in 
general with the contents of actual and possible beliefs, 
and we may say that it is propositions that are true or 
false. In logic we are concerned with propositions rather 
than beliefs, since logic is not interested in what people 


do in fact believe, but only in the conditions which 
determine the truth or falsehood of possible beliefs. 
Whenever possible, except when actual beliefs are in 
question, it is generally a simplification to deal with 

It would seem that image-propositions are more primi- 
tive than word-propositions, and may well ante-date 
language. There is no reason why memory-images, 
accompanied by that very simple belief-feeling which 
we decided to be the essence of memory, should not have 
occurred before language arose ; indeed, it would be rash 
to assert positively that memory of this sort does not 
occuf among the higher animal^, Our more elementary 
beliefs, notably those that are added to sensation to 
make perception, often remain at the level of images. 
For example, most of the visual objects in our neighbour- 
hood rouse tactile images : we have a different feeling 
in looking at a sofa from what we have in looking at a 
block of marble, and the difference consists chiefly in 
different stimulation of our tactile imagination. It may 
be said that the tactile images are merely present, without 
any accompanying belief ; but I think this view, though 
sometimes correct, derives its plausibility as a general 
proposition from our thinking of explicit conscious belief 
only. Most of our beliefs, like most of our wishes, are 
" unconscious," in the sense that we have never told 
ourselves that we have them. Such beliefs display them- 
selves when the expectations that they arouse fail in any 
way. For example, if someone puts tea (without milk) 
into a glass, and you drink it under the impression that 
it is going to be beer ; or if you walk on what appears 
to be a tiled floor, and it turns out to be a soft carpet 
made to look like tiles. The shock of surprise on an 


occasion of this kind makes us aware of the expectations 
that habitually enter into our perceptions ; and such 
expectations must be classed as beliefs, in spite of the 
fact that we do not normally take note of them or put 
them into words. I remember once watching a cock 
pigeon running over and over again to the edge of a 
looking-glass to try to wreak vengeance on the particu- 
larly obnoxious bird whom he expected to find there, 
judging by what he saw in the glass. He must have 
experienced each time the sort of surprise on finding 
nothing, which is calculated to lead in time to the adop- 
tion of Berkeley's theory that objects of sense are only 
in the mind. His expectation, though not expressed in 
words, deserved, I think, to be called a belief. 

I come now to the question what constitutes believing, 
as opposed to the content believed. 

To begin with, there are various different attitudes 
that may be taken towards the same content. Let us 
suppose, for the sake of argument, that you have a visual 
image of your breakfast-table. You may expect it while 
you are dressing in the morning ; remember it as you 
go to your work ; feel doubt as to its correctness when 
questioned as to your powers of visualizing ; merely 
entertain the image, without connecting it with anything 
external, when you are going to sleep ; desire it if you 
are hungry, or feel aversion for it if you are ill. Suppose, 
for the sake of definiteness, that the content is "an egg 
for breakfast/' Then you have the following attitudes : 
" I expect there will be an egg for breakfast " ; "I 
remember there was an egg for breakfast " ; " Was there 
an egg for breakfast ? " "An egg for breakfast : well, 
what of it ? " "I hope there will be an egg for break- 
fast " ; "I am afraid there will be an egg for breakfast 


and it is sure to be bad/' I do not suggest that this 
is a list of all possible attitudes on the subject ; I say 
only that they are different attitudes, all concerned with 
the one content " an egg for breakfast." 

These attitudes are not all equally ultimate. Those 
that involve desire and aversion have occupied us in 
Lecture III. For the present, we are only concerned 
with such as are cognitive. In speaking of memory, 
we distinguished three kinds of belief directed towards 
the same content, namely memory, expectation and 
bare assent without any time-determination in the belief- 
feeling. But before developing this view, we must 
examine two other theories which might be held con- 
cerning belief, and which, in some ways, would be more 
in harmony with a behaviourist outlook than the theory 
I wish to advocate. 

(i) The first theory to be examined is the view that 
the differentia of belief consists in its causal efficacy. 
I do not wish to make any author responsible for this 
theory : I wish merely to develop it hypothetically so 
that we may judge of its tenability. 

We defined the meaning of an imag$ or word by causal 
efficacy, namely by associations : an image or word 
acquires meaning, we said, through having the same 
associations as what it means. 

We propose hypothetically to define " belief " by a 
different kind of causal efficacy, namely efficacy in 
causing voluntary movements. (Voluntary movements 
are defined as those vital movements which are dis- 
tinguished from reflex movements as involving the higher 
nervous centres. I do not like to distinguish them by 
means of such notions as " consciousness " or " will," 
because I do not think these notions, in any definable 


sense, are always applicable. Moreover, the purpose of 
the theory we are examining is to be, as far as possible, 
physiological and behaviourist, and this purpose is not 
achieved if we introduce such a conception as " con- 
sciousness " or " will." Nevertheless, it is necessary 
for our purpose to find some way of distinguishing between 
voluntary and reflex movements, since the results would 
be too paradoxical, if we were to say that reflex move- 
ments also involve beliefs.) According to this definition, 
a content is said to be " believed " when it causes us to 
move. The images aroused are the same if you say to 
me, " Suppose there were an escaped tiger coming along 
the street, 1 ' and if you say to me, " There is an escaped 
tiger coming along the street." But my actions will be 
very different in the two cases : in the first, I shall 
remain calm ; in the second, it is possible that I may not. 
It is suggested, by the theory we are considering, that 
this difference of effects constitutes what is meant by 
saying that in the second case I believe the proposition 
suggested, while in the first case I do not. According 
to this view, images or words are " believed " when they 
cause bodily movements. 

I do not think this theory is adequate, but I think 
it is suggestive of truth, and not so easily refutable as 
it might appear to be at first sight. 

It might be objected to the theory that many things 
which we certainly believe do not call for any bodily 
movements. I believe that Great Britain is an island, 
that whales are mammals, that Charles I was executed, 
and so on ; and at first sight it seems obvious that such 
beliefs, as a rule, do not call for any action on my part. 
But when we investigate the matter morg closely, it 
becomes more doubtful. To begin with, we must dis- 


tinguish belief as a mere disposition from actual active 
belief. We speak as if we always believed that Charles I 
was executed, but that only means that we are always 
ready to believe it when the subject comes up. The 
phenomenon we are concerned to analyse is the active 
belief, not the permanent disposition. Now, what are 
the occasions when we actively believe that Charles I 
was executed ? Primarily : examinations, when we per- 
form the bodily movement of writing it down ; con- 
versation, when we assert it to display our historical 
erudition ; and political discourses, when we are engaged 
in showing what Soviet government leads to. In all 
these .cases bodily movements (writing or speaking) 
result from our belief. 

But there remains the belief which merely occurs in 
" thinking." One may set to work to recall some piece 
of history one has been reading, and what one recalls 
is believed, although it probably does not cause any 
bodily movement whatever. It is true that what we 
believe always may influence action. Suppose I am 
invited to become King of Georgia : I find the prospect 
attractive, and go to Cook's to buy a third-class ticket 
to my new realm. At the last moment I remember 
Charles I and all the other monarchs who have come 
to a bad end ; I change my mind, and walk out without 
completing the transaction. But such incidents are rare, 
and cannot constitute the whole of my belief that 
Charles I was executed. The conclusion seems to be 
that, although a belief always may influence action if 
it becomes relevant to a practical issue, it often exists 
actively (not as a mere disposition) without producing 
any voluntary movement whatever. If this is true, we 
cannot define belief by the effect on voluntary movements. 


There is another, more theoretical, ground for rejecting 
the view we are examining. It is clear that a proposition 
can be either believed or merely considered, and that 
the content is the same in both cases. We can expect 
an egg for breakfast, or merely entertain the supposition 
that there may be an egg for breakfast. A moment 
ago I considered the possibility of being invited to become 
King of Georgia, but I do not believe that this will happen. 
Now, it seems clear that, since believing and considering 
have different effects if one produces bodily movements 
while the other does not, there must be some intrinsic 
difference between believing and considering x ; for if 
they were precisely similar, their effects also would be 
precisely similar. We have seen that the difference 
between believing a given proposition and merely con- 
sidering it does not lie in the content ; therefore there 
must be, in one case or in both, something additional 
to the content which distinguishes the occurrence of a 
belief from the occurrence of a mere consideration of 
the same content. So far as the theoretical argument 
goes, this additional element may exist only in belief, 
or only in consideration, or there may be one sort of 
additional element in the case of belief, and another in 
the case of consideration. This brings us to the second 
view which we have to examine. 

(2) The theory which we have now to consider regards 
belief as belonging to every idea which is entertained, 
except in so far as some positive counteracting force 
interferes. In this view belief is not a positive pheno- 
menon, though doubt and disbelief are so. What we 
call belief, according to this hypothesis, involves only 

' Cf. Brentano, Psyckologie vom empiriscken St*ndpttnkte t p. 268 
(criticizing Bain, The Emotions and the Will). 


the appropriate content, which will have the effects 
characteristic of belief unless something else operating 
simultaneously inhibits them. James (Psychology, vol. ii, 
p. 288) quotes with approval, though inaccurately, a 
passage from Spinoza embodying this view : 

" Let us conceive a boy imagining to himself a horse, 
and taking note of nothing else. As this imagination 
involves the existence of the horse, and the boy has no 
perception which annuls its existence [James's italics], he 
will necessarily contemplate the horse as present, nor 
will he be able to doubt of its existence, however little 
certain of it he may be. I deny that a man in so far 
as he imagines [percipit] affirms nothing. For what is 
it to imagine a winged horse but to affirm that the horse 
[that horse, namely] has wings ? For if the mind had 
nothing before it but the winged horse, it would contem- 
plate the same as present, would have no cause to doubt 
of its existence, nor any power of dissenting from its 
existence, unless the imagination of the winged horse 
were joined to an idea which contradicted [tollit] its 
existence " (Ethics, vol. ii, p. 49, Scholium). 

To this doctrine James entirely assents, adding in 
italics : 

"Any object which remains uncontradicted is ipso facto 
believed and posited as absolute reality/' ^ " " * 

If this view is correct, it follows (though James does 
not draw the inference) that there is no need of any 
specific feeling called " belief," and that the mere exist- 
ence of images yields all that is required. The state of 
mind in which we merely consider a proposition, without 
believing or disbelieving it, will then appear as a sophisti- 
cated product, the result of some rival force adding to 
the image-proposition a positive feeling which may be 


called suspense or non-belief a feeling which may be 
compared to that of a man about to run a race waiting 
for the signal. Such a man, though not moving, is in 
a very different condition from that of a man quietly 
at rest. And so the man who is considering a proposition 
without believing it will be in a state of tension, restrain- 
ing the natural tendency to act upon the proposition 
which he would display if nothing interfered. In this 
view belief primarily consists merely in the existence 
of the appropriate images without any counteracting 

There is a great deal to be said in favour of this view, 
and I have some hesitation in regarding it as inadequate. 
It fits admirably with the phenomena of dreams and 
hallucinatory images, and it is recommended by the 
way in which it accords with mental development. Doubt, 
suspense of judgment and disbelief all seem later and 
more complex than a wholly unreflecting assent. Belief 
as a positive phenomenon, if it exists, may be regarded, 
in this view, as a product of doubt, a decision after debate, 
an acceptance, not merely of this, but of this-rather-than- 
that. It is not difficult to suppose that a dog has images 
(possible olfactory) of his absent master, or of the rabbit 
that he dreams of hunting. But it is very difficult to 
suppose that he can entertain mere imagination-images 
to which no assent is given. 

I think it must be conceded that a mere image, without 
the addition of any positive feeling that could be called 
" belief," is apt to have a certain dynamic power, and 
in this sense an uncombated image has the force of a 
belief. But although this may be true, it accounts only 
for some of the simplest phenomena in the region of 
belief. It will not, for example, explain memory. Nor 


can it explain beliefs which do not issue in any proximate 
action, such as those of mathematics. I conclude, there- 
fore, that there must be belief-feelings of the same order 
as those of doubt or disbelief, although phenomena closely 
analogous to those of belief can be produced by mere 
uncontradicted images. 

(3) I come now to the view of belief which I wish to 
advocate. It seems to me that there are at least three 
kinds of belief, namely memory, expectation and bare 
assent. Each of these I regard as constituted by a 
certain feeling or complex of sensations, attached to the 
content believed. We may illustrate by an example. 
Suppose I am believing, by means of images, not words, 
that it will rain. We have here two interrelated ele- 
ments, namely the content and the expectation. The 
content consists of images of (say) the visual appearance 
of rain, the feeling of wetness, the patter of drops, inter- 
related, roughly, as the sensations would be if it were 
raining. Thus the content is a complex fact composed 
of images. Exactly the same content may enter into 
the memory " it was raining " or the assent " rain occurs." 
The difference of these cases from each other and from 
expectation does not lie in the content. The difference 
lies in the nature of the belief-feeling. I, personally, 
do not profess to be able to analyse the sensations con- 
stituting respectively memory, expectation and assent ; 
but I am not prepared to say that they cannot be analysed. 
There may be other belief -feelings, for example in dis- 
junction and implication ; also a disbelief-feeling. 

It is not enough that the content and the belief-feeling 
should co-exist : it is necessary that there should be a 
specific relation between them, of the sort expressed by 
saying that the content is what is believed. If this 



were not obvious, it could be made plain by an argument. 
If the mere co-existence of the content and the belief- 
feeling sufficed, whenever we were having (say) a memory- 
feeling we should be remembering any proposition which 
came into our minds at the same time. But this is not 
the case, since we may simultaneously remember one 
proposition and merely consider another. 

We may sum up our analysis, in the case of bare assent 
to a proposition not expressed in words, as follows : 
(a) We have a proposition, consisting of interrelated 
images, and possibly partly of sensations ; (b) we have 
the feeling of assent, which is presumably a complex 
sensation demanding analysis ; (c) we have a relation, 
actually subsisting, between the assent and the proposi- 
tion, such as is expressed by saying that the proposition 
in question is what is assented to. For other forms of 
belief -feeling or of content, we have only to make the 
necessary substitutions in this analysis. 

If we are right in our analysis of belief, the use of 
words in expressing beliefs is apt to be misleading. There 
is no way of distinguishing, in words, between a memory 
and an assent to a proposition about the past : "I ate 
my breakfast " and " Csesar conquered Gaul " have the 
same verbal form, though (assuming that I remember 
my breakfast) they express occurrences which are psycho- 
logically very different. In the one case, what happens 
is that I remember the content " eating my breakfast " ; 
in the other case, I assent to the content " Caesar's con- 
quest of Gaul occurred/' In the latter case, but not 
in the former, the pastness is part of the content believed. 
Exactly similar remarks apply to the difference between 
expectation, such as we have when waiting for the 
thunder after a flash of lightning, and assent to a propo- 


sit ion about the future, such as we have in all the usual 
cases of inferential knowledge as to what will occur. 
I think this difficulty in the verbal expression* of the 
temporal aspects of beliefs is one among the causes which 
have hampered philosophy in the consideration of time. 
The view of belief which I have been advocating con- 
tains little that is novel except the distinction of kinds 
of belief -feeling such as memory and expectation. Thus 
James says : " Everyone knows the difference between 
imagining a thing and believing in its existence, between 
supposing a proposition and acquiescing in its truth. . . . 
In its inner nature, belief, or the sense of reality, is a sort 
of feeling more allied to the emotions than to anything else " 
(Psychology, vol. ii, p. 283. James's italics). He proceeds 
to point out that drunkenness, and, still more, nitrous- 
oxide intoxication, will heighten the sense of belief : in 
the latter case, he says, a man's very soul may sweat 
with conviction, and he be all the time utterly unable 
to say what he is convinced of. It would seem that, 
in such cases, the feeling of belief exists unattached, 
without its usual relation to a content believed, just 
as the feeling of familiarity may sometimes occur without 
being related to any definite familiar object. The feeling 
of belief, when it occurs in this separated heightened 
form, generally leads us to look for a content to which 
to attach it. Much of what passes for revelation or 
mystic insight probably comes in this way : the belief- 
feeling, in abnormal strength, attaches itself, more or 
less accidentally, to some content which we happen to 
think of at the appropriate moment. But this is only 
a speculation, upon which I do not wish to lay too much 


THE definition of truth and falsehood, which is our topic 
to-day, lies strictly outside our general subject, namely 
the analysis of mind. From the psychological stand- 
point, there may be different kinds of belief, and different 
degrees of certainty, but there cannot be any purely 
psychological means of distinguishing between true and 
false beliefs. A belief is rendered true or false by relation 
to a fact, which may lie outside the experience of the 
person entertaining the belief. Truth and falsehood, 
except in the case of beliefs about our own minds, depend 
upon the relations of mental occurrences to outside things, 
and thus take us beyond the analysis of mental occur- 
rences as they are in themselves. Nevertheless, we can 
hardly avoid the consideration of truth and falsehood. 
We wish to believe that our beliefs, sometimes at least, 
yield knowledge, and a belief does not yield knowledge 
unless it is true. The question whether our minds are 
instruments of knowledge, and, if so, in what sense, is 
so vital that any suggested analysis of mind must be 
examined in relation to this question. To ignore this 
question would be like describing a chronometer without 
regard to its accuracy as a time-keeper, or a thermometer 

without mentioning the fact that it measures temperature. 



Many difficult questions arise in connection with 
knowledge. It is difficult to define knowledge, difficult 
to decide whether we have any knowledge, and difficult, 
even if it is conceded that we sometimes have knowledge, 
to discover whether we can ever know that we have 
knowledge in this or that particular case. I shall divide 
the discussion into four parts : 

I. We may regard knowledge, from a behaviourist 
standpoint, as exhibited in a certain kind of response 
to the environment. This response must have some 
characteristics which it shares with those of scientific 
instruments, but must also have others that are peculiar 
to knowledge. We shall find that this point of view is 
important, but not exhaustive of the nature of knowledge. 

II. We may hold that the beliefs that constitute know- 
ledge are distinguished from such as are erroneous or 
uncertain by properties which are intrinsic either to 
single beliefs or to systems of beliefs, being in either case 
discoverable without reference to outside fact. Views 
of this kind have been widely held among philosophers, 
but we shall find no reason to accept them. 

III. We believe that some beliefs are true, and some 
false. This raises the problem of verifidbility : are there 
any circumstances which can justifiably give us an un- 
usual degree of certainty that such and such a belief is 
true ? It is obvious that there are circumstances which 
in fact cause a certainty of this sort, and we wish to 
learn what we can from examining these circumstances. 

IV. Finally, there is the formal problem of defining 
truth and falsehood, and deriving the objective reference 
of a proposition from the meanings of its component 

We will consider these four problems in succession. 


I. We may regard a human being as an instrument, 
which makes various responses to various stimuli. If 
we observe these responses from outside, we shall regard 
them as showing knowledge when they display two 
characteristics, accuracy and appropriateness. These two 
are quite distinct, and even sometimes incompatible. 
If I am being pursued by a tiger, accuracy is furthered 
by turning round to look at him, but appropriateness 
by running away without making any search for further 
knowledge of the beast. I shall return to the question 
of appropriateness later ; for the present it is accuracy 
that I wish to consider. 

When we are viewing a man from the outside, it is not 
his beliefs, but his bodily movements, that we can observe. 
His knowledge must be inferred from his bodily move- 
ments, and especially from what he says and writes. 
For the present we may ignore beliefs, and regard a 
man's knowledge as actually consisting in what he says 
and does. That is to say, we will construct, as far as 
possible, a purely behaviouristic account of truth and 

If you ask a boy " What is twice two ? " and the boy 
says "four," you take that as prima facie evidence that 
the boy knows what twice two is. But if you go on to 
ask what is twice three, twice four, twice five, and so on, 
and the boy always answers " four/' you come to the 
conclusion that he knows nothing about it. Exactly 
similar remarks apply to scientific instruments. I know 
a certain weather-cock which has the pessimistic habit 
of always pointing to the north-cast. If you were to 
see it first on a cold March day, you would think it an 
excellent weather-cock ; but with the first warm day 
of spring your confidence would be shaken. The boy 


and the weather-cock have the same defect : they do not 
vary their response when the stimulus is varied. A good 
instrument, or a person with much knowledge, will give 
different responses to stimuli which differ in relevant 
ways. This is the first point in defining accuracy of 

We will now assume another boy, who also, when 
you first question him, asserts that twice two is four. 
But with this boy, instead of asking him different ques- 
tions, you make a practice of asking him the same question 
every day at breakfast. You find that he says five, 
of *sfx, or seven, or any other number at random, and 
you conclude that he also does not know what twice 
two is, though by good luck he answered right the first 
time. This boy is like a weather-cock which, instead 
of being stuck fast, is always going round and round, 
changing without any change of wind. This boy and 
weather-cock have the opposite defect to that of the 
previous pair : they give different responses to stimuli 
which do not differ in any relevant way. 

In connection with vagueness in memory, we already 
had occasion to consider the definition of accuracy. 
Omitting some of the niceties of our previous discussion, 
we may say that an instrument is accurate when it avoids 
the defects of the two boys and weather-cocks, that is 
to say, when 

(a) It gives different responses to stimuli which 

differ in relevant ways ; 

(b) It gives the same response to stimuli which do 

not differ in relevant ways. 

What are relevant ways depends upon the nature and 
purpose of the instrument. In the case of a weather- 


cock, the direction of the wind is relevant, but not its 
strength ; in the case of the boy, the meaning of the 
words of your question is relevant, but not the loudness 
of your voice, or whether you are his father or his school- 
master. If, however, you were a boy of his own age, 
that would be relevant, and the appropriate response 
would be different. 

It is clear that knowledge is displayed by accuracy 
of response to certain kinds of stimuli, e.g. examinations. 
Can we say, conversely, that it consists wholly of such 
accuracy of response ? I do not think we can ; but 
we can go a certain distance in this direction. For this 
purpose we must define more carefully the kind of 
accuracy and the kind of response that may be expected 
where there is knowledge. 

From our present point of view, it is difficult to exclude 
perception from knowledge ; at any rate, knowledge is 
displayed by actions based upon perception. A bird 
flying among trees avoids bumping into their branches ; 
its avoidance is a response to visual sensations. This 
response has the characteristic of accuracy, in the main, 
and leads us to say that the bird " knows/' by sight, 
what objects are in its neighbourhood. For a behaviourist, 
this must certainly count as knowledge, however it may 
be viewed by analytic psychology. In this case, what 
is known, roughly, is the stimulus ; but in more advanced 
knowledge the stimulus and what is known become 
different. For example, you look in your calendar and 
find that Easter will be early next year. Here the 
stimulus is the calendar, whereas the response concerns 
the future. Even this can be paralleled among instru- 
ments : the behaviour of the barometer has a present 
stimulus, but foretells the future, so that the barometer 



might be said, in a sense, to know the future. However 
that may be, the point I am emphasizing as regards 
knowledge is that what is known may be quite different 
from the stimulus, and no part of the cause of the know- 
ledge-response. It is only in sense-knowledge that the 
stimulus and what is known are, with qualifications, 
identifiable. In knowledge of the future, it is obvious 
that they are totally distinct, since otherwise the response 
would precede the stimulus. In abstract knowledge 
also they are distinct, since abstract facts have no date. 
In knowledge of the past there are complications, which 
we must briefly examine. 

Every form of memory will be, from our present point 
of view, in one sense a delayed response. But this phrase 
does not quite clearly express what is meant. If you 
light a fuse and connect it with a heap of dynamite, 
the explosion of the dynamite may be spoken of, in a 
sense, as a delayed response to your lighting of the fuse. 
But that only means that it is a somewhat latq portion 
of a continuous process of which the earlier parts have 
less emotional interest. This is not the case with habit. 
A display of habit has two sorts of causes : (a) the past 
occurrences which generated the habit, (6) the present 
occurrence which brings it into play. When you drop 
a weight on your toe, and say what you do say, the habit 
has been caused by imitation of your undesirable asso- 
ciates, whereas it is brought into play by the dropping 
of the weight. The great bulk of our knowledge is a 
habit in this sense : whenever I am asked when I was 
born, I reply correctly by mere habit. It would hardly 
be correct to say that getting born was the stimulus, 
and that my reply is a delayed response. But in cases 
of memory this way of speaking would have an element 


of truth. In an habitual memory, the event remembered 
was clearly an essential part of the stimulus to the for- 
mation of the habit. The present stimulus which brings 
the habit into play produces a different response from 
that which it would produce if the habit did not exist. 
Therefore the habit enters into the causation of the 
response, and so do, at one remove, the causes of the 
habit. It follows that an event remembered is an essential 
part of the causes of our remembering. 

In spite, however, of the fact that what is known is 
sometimes an indispensable part of the cause of the know- 
ledge, this circumstance is, I think, irrelevant to the 
general question with which we are concerned, namely : 
What sort of response to what sort of stimulus can be 
regarded as displaying knowledge ? There is one char- 
acteristic which the response must have, namely, it must 
consist of voluntary movements. The need of this 
characteristic is connected with the characteristic of 
appropriateness, which I do not wish to consider as yet. 
For the present I wish only to obtain a clearer idea of 
the sort of accuracy that a knowledge-response must 
have. It is clear from many instances that accuracy, 
in other cases, may be purely mechanical. The most 
complete form of accuracy consists in giving correct 
answers to questions, an achievement in which calcu- 
lating machines far surpass human beings. In asking a 
question of a calculating machine, you must use its 
language : you must not address it in English, any more 
than you would address an Englishman in Chinese. But 
if you address it in the language it understands, it will 
tell you what is 34521 times 19987, without a moment's 
hesitation or a hint of inaccuracy. We do not say the 
machine knows the answer, because it has no purpose 


of its own in giving the answer : it does not wish to 
impress you with its cleverness, or feel proud of being 
such a good machine. But as far as mere accuracy goes, 
the machine leaves nothing to be desired. 

Accuracy of response is a perfectly clear notion in the 
case of answers to questions, but in other cases it is much 
more obscure. We may say generally that an object 
whether animate or inanimate, is " sensitive " to a certain 
feature of the environment if it behaves differently accord- 
ing to the presence or absence of that feature. Thus 
iron is sensitive to anything magnetic. But sensitive- 
ness does not constitute knowledge, and knowledge of a 
fact which is not sensible is not sensitiveness to that 
fact, as we have seen in distinguishing the fact known 
from the stimulus. As soon as we pass beyond the simple 
case of question and answer, the definition of knowledge 
by means of behaviour demands the consideration of 
purpose. A carrier pigeon flies home, and so we say it 
" knows " the way. But if it merely flew to some place 
at random, we should not say that it " knew " the way 
to that place, any more than a stone rolling down hill 
knows the way to the valley. 

On the features which distinguish knowledge from 
accuracy of response in general, not much can be said 
from a behaviourist point of view without referring to 
purpose. But the necessity of something besides accuracy 
of response may be brought out by the following con- 
sideration : Suppose two persons, of whom one believed 
whatever the other disbelieved, and disbelieved whatever 
the other believed. So far as accuracy and. sensitiveness 
of response alone are concerned, there would be nothing 
to choose between these two persons. A thermometer 
which went down for warm weather and up for cold 


might be just as accurate as the usual kind ; and a person 
who always believes falsely is just as sensitive an instru- 
ment as a person who always believes truly. The observ- 
able and practical difference between them would be 
that the one who always believed falsely would quickly 
come to a bad end. This illustrates once more that 
accuracy of response to stimulus does not alone show 
knowledge, but must be reinforced by appropriateness, 
i.e. suitability for realizing one's purpose. This applies 
even in the apparently simple case of answering ques- 
tions : if the purpose of the answers is to deceive, their 
falsehood, not their truth, will be evidence of knowledge. 
The proportion of the combination of appropriateness 
with accuracy in the definition of knowledge is difficult ; 
it seems that both enter in, but that appropriateness is 
only required as regards the general type of response, 
not as regards each individual instance. 

II. I have so far assumed as unquestionable the view 
that the truth or falsehood of a belief consists in a relation 
to a certain fact, namely the objective of the belief. 
This view has, however, been often questioned. Philo- 
sophers have sought some intrinsic criterion by which 
true and false beliefs could be distinguished. 1 I am 

1 The view that such a criterion exists is generally held by those 
whose views are in any degree derived from Hegel. It may be 
illustrated by the following passage from Lossky, The Intuitive 
Basis of Knowledge (Macmillan, 1919), p. 268 : " Strictly speaking, 
a false judgment is not a judgment at all. The predicate does 
not follow from the subject S alone, but from the subject plus 
a certain addition C, which in no sense belongs to the content of the 
judgment. What takes place may be a process of association of 
ideas, of imagining, or the like, but is not a process of judging. 
An experienced psychologist will be able by careful observation 
to detect that in this process there is wanting just the specific 
element of the objective dependence of the predicate upon the 
subject which is characteristic of a judgment. It must be admitted, 


afraid their chief reason for this search has been the 
wish to feel more certainty than seems otherwise possible 
as to what is true and what is false. If we could discover 
the truth of a belief by examining its intrinsic charac- 
teristics, or those of some collection of beliefs of which 
it forms patt, the pursuit of truth, it is thought, would 
be a less arduous business than it otherwise appears to 
be. But the attempts which have been made in this 
direction are not encouraging. I will take two criteria 
which have been suggested, namely, (i) self-evidence, 
(2) mutual coherence. If we can show that these are 
inadequate, we may feel fairly certain that no intrinsic 
criterion hitherto suggested will suffice to distinguish 
true from false beliefs. 

(i) Self-evidence. Some of our beliefs seem to be 
peculiarly indubitable. One might instance the belief 
that two and two are four, that two things cannot be 
in the same place at the same time, nor one thing in 
two places, or that a particular buttercup that we are 
seeing is yellow. The suggestion we are to examine is 
that such beliefs have some recognizable quality which 
secures their truth, and the truth of whatever is deduced 
from them according to self-evident principles of inference. 
This theory is set forth, for example, by Meinong in his 
book, Ueber die Erfahrungsgrundlagen unseres Wissens. 

If this theory is to be logically tenable, self-evidence 
must not consist merely in the fact that we believe a 
proposition. We believe that our beliefs are sometimes 
erroneous, and we wish to be able to select a certain 
class of beliefs which are never erroneous. If we are 

however, that an exceptional power of observation is needed in 
order to distinguish, by means of introspection, mere combinations 
of ideas from judgments." 


to do this, it must be by some mark which belongs only 
to certain beliefs, not to all ; and among those to which 
it belongs there must be none that are mutually incon- 
sistent. If, for example, two propositions p and q were 
self-evident, and it were also self-evident that p and q 
could not both be true, that would condemn self-evidence 
as a guarantee of truth. Again, self-evidence must not 
be the same thing as the absence of doubt or the presence 
of complete certainty. If we are completely certain of 
a proposition, we do not seek a ground to support our 
belief. If self-evidence is alleged as a ground of belief, 
that implies that doubt has crept in, and that our self- 
evident proposition has not wholly resisted the assaults 
of scepticism. To say that any given person believes 
some things so firmly that he cannot be made to doubt 
them is no doubt true. Such beliefs he will be willing 
to use as premisses in reasoning, and to him personally 
they will seem to have as much evidence as any belief 
can need. But among the propositions which one man 
finds indubitable there will be some that another man 
finds il; quite possible to doubt. It used to seem self- 
evident that there could not be men at the Antipodes, 
because they would fall off, or at best grow giddy from 
standing on their heads. But New Zealanders find the 
falsehood of this proposition self-evident. Therefore, if 
self-evidence is a guarantee of truth, our ancestors must 
have been mistaken in thinking their beliefs about the 
Antipodes self-evident. Meinong meets this difficulty 
by saying that some beliefs are falsely thought to be 
self-evident, but in the case of others it is self-evident 
that they are self-evident, and these are wholly reliable. 
Even this, however, does not remove the practical risk 
of error, since we may mistakenly believe it self-evident 


that a certain belief is self-evident. To remove all risk 
of error, we shall need an endless series of more and more 
complicated self-evident beliefs, which cannot possibly 
be realized in practice. It would seem, therefore, that 
self-evidence is useless as a practical criterion for insuring 

The same result follows from examining instances. 
If we take the four instances mentioned at the beginning 
of this discussion, we shall find that three of them are 
logical, while the fourth is a judgment of perception. 
The proposition that two and two are four follows by 
purely logical deduction from definitions : that means 
that .its truth results, not from the properties of objects, 
but from the meanings of symbols. Now symbols, in 
mathematics, mean what we choose ; thus the feeling 
of self-evidence, in this case, seems explicable by the 
fact that the whole matter is within our control. I do 
not wish to assert that this is the whole truth about 
mathematical propositions, for the question is com- 
plicated, and I do not know what the whole truth is. 
But I do wish to suggest that the feeling of self-evidence 
in mathematical propositions has to do with the fact 
that they are concerned with the meanings of symbols, 
not with properties of the world such as external observa- 
tion might reveal. 

Similar considerations apply to the impossibility of 
a thing being in two places at once, or of two things 
being in one place at the same time. These impossibilities 
result logically, if I am not mistaken, from the definitions 
of one thing and one place. That is to say, they are not 
laws of physics, but only part of the intellectual apparatus 
which we have manufactured for manipulating physics. 
Their self-evidence, if this is so, lies merely in the fact 


that they represent our decision as to the use of words, 
not a property of physical objects. 

Judgments of perception, such as " this buttercup is 
yellow," are in a quite different position from judgments 
of logic, and their self-evidence must have a different 
explanation. In order to arrive at the nucleus of such 
a judgment, we will eliminate, as far as possible, the use 
of words which take us beyond the present fact, such 
as " buttercup " and " yellow." The simplest kind of 
judgment underlying the perception that a buttercup is 
yellow would seem to be the perception of similarity in 
two colours seen simultaneously. Suppose we are 
seeing two buttercups, and we perceive that their 
colours are similar. This similarity is a physical fact, 
not a matter of symbols or words ; and it certainly 
seems to be indubitable in a way that many judgments 
are not. 

The first thing to observe, in regard to such judgments, 
is that as they stand they are vague. The word " similar " 
is a vague word, since there are degrees of similarity, 
and no one can say where similarity ends and dis- 
similarity begins. It is unlikely that our two buttercups 
have exactly the same colour, and if we judged that they 
had we should have passed altogether outside the region 
of self-evidence. To make our proposition more precise, 
let us suppose that we are also seeing a red rose at the 
same time. Then we may judge that the colours of the 
buttercups are more similar to each other than to the 
colour of the rose. This judgment seems more com- 
plicated, ~ but has certainly gained in precision. Even 
now, however, it falls short of complete precision, since 
similarity is not prima facie measurable, and it would 
require much discussion to decide what we mean by 


greater or less similarity. To this process of the pursuit 
of precision there is strictly no limit. 

The next thing to observe (although I do not personally 
doubt that most of our judgments of perception are true) 
is that it is very difficult to define any class of such judg- 
ments which can be known, by its intrinsic quality, to 
be always exempt from error. Most of our judgments 
of perception involve correlations, as when we judge 
that a certain noise is that of a passing cart. Such 
judgments are all obviously liable to error, since there 
is no correlation of which we have a right to be certain 
that it is invariable. Other judgments of perception are 
derived from recognition, as when we say " this is a 
buttercup," or even merely " this is yellow." All such 
judgments entail some risk of error, though sometimes 
perhaps a very small one ; some flowers that look like 
buttercups are marigolds, and colours that some would 
call yellow others might call orange. Our subjective 
certainty is usually a result of habit, and may lead us 
astray in circumstances which are unusual in ways of 
which we are unaware. 

For such reasons, no form of self-evidence seems to 
afford an absolute criterion of truth. Nevertheless, it 
is perhaps true that judgments having a high degree of 
subjective certainty are more apt to be true than other 
judgments. But if this be the case, it is a result to be 
demonstrated, not a premiss from which to start in 
defining truth and falsehood. As an initial guarantee, 
therefore, neither self -evidence nor subjective certainty 
can be accepted as adequate. 

(2) Coherence. Coherence as the definition of truth is 
advocated by idealists, particularly by those who in the 
main follow Hegel. It is set forth ably in Mr. Joachim's 


book, The Nature of Truth (Oxford, 1906). According to 
this view, any set of propositions other than the whole 
of truth can be condemned on purely logical grounds, 
as internally inconsistent ; a single proposition, if it is 
what we should ordinarily call false, contradicts itself 
irremediably, while if it is what we should ordinarily 
call true, it has implications which compel us to admit 
other propositions, which in turn lead to others, and 
so on, until we find ourselves committed to the whole 
of truth. One might illustrate by a very simple example : 
if I say " so-and-so is a married man," that is not a self- 
subsist ent proposition. We cannot logically conceive of 
a universe in which this proposition constituted the whole 
of truth. There must be also someone who is a married 
woman, and who is married to the particular man in 
question. The view we are considering regards every- 
thing that can be said about any one object as relative 
in the same sort of way as " so-and-so is a married man." 
But everything, according to this view, is relative, not 
to one or two other things, but to all other things, so 
that from one bit of truth the whole can be inferred. 

The fundamental objection to this view is logical, 
and consists in a criticism of its doctrine as to relations. 
I shall omit this line of argument, which I have developed 
elsewhere. 1 For the moment I will content myself 
with saying that the powers of logic seem to me very 
much less than this theory supposes. If it were taken 
seriously, its advocates ought to profess that any one 
truth is logically inferable from any other, and that, 
for example, the fact that Caesar conquered Gaul, if 

1 In the article on " The Monistic Theory of Truth " in Philo- 
sophical Essays (Longmans, 1910), reprinted from the Proceedings 
of the Aristotelian Society, 1906-7. 


adequately considered, would enable us to discover what 
the weather will be to-morrow. No such claim is put 
forward in practice, and the necessity of empirical ob- 
servation is not denied ; but according to the theory 
it ought to be. 

Another objection is that no endeavour is made to 
show that we cannot form a consistent whole composed 
partly or wholly of false propositions, as in a novel. 
Leibniz's conception of many possible worlds seems to 
accord much better with modern logic and with the 
practical empiricism which is now universal. The attempt 
to deduce the world by pure thought is attractive, and 
in former times was largely supposed capable of success. 
But nowadays most men admit that beliefs must be 
tested by observation, and not merely by the fact that 
they harmonize with other beliefs. A consistent fairy- 
tale is a different thing from truth, however elaborate 
it may be. But to pursue this topic would lead us into 
difficult technicalities ; I shall therefore assume, without 
further argument, that coherence is not sufficient as a 
definition of truth. 

III. Many difficult problems arise as regards the 
verifiability of beliefs. We believe various things, and 
while we believe them we think we know them. But 
it sometimes turns out that we were mistaken, or at 
any rate we come to think we were. We must be mistaken 
either in our previous opinion or in our subsequent re- 
cantation ; therefore our beliefs are not all correct, and 
there are cases of belief which are not cases of knov/ledge. 
The question of verifiability is in essence this : can we 
discover any set of beliefs which are never mistaken, 
or any test which, when applicable, will always enable 
us to discriminate between true and false beliefs ? Put 


thus broadly and abstractly, the answer must be negative. 
There is no way hitherto discovered of wholly eliminating 
the risk of error, and no infallible criterion. If we believe 
we have found a criterion, this belief itself may be mis- 
taken ; we should be begging the question if we tried 
to test the criterion by applying the criterion to itself. 

But although the notion of an absolute criterion is 
chimerical, there may be relative criteria, which increase 
the probability of truth. Common sense and science hold 
that there are. Let us see what they have to say. 

One of the plainest cases of verification, perhaps ulti- 
mately the only case, consists in the happening of some- 
thing expected. You go to the station believing that 
there will be a train at a certain time ; you find the 
train, you get into it, and it starts at the expected time 
This constitutes verification, and is a perfectly definite 
experience. It is, in a sense, the converse of memory : 
instead of having first sensations and then images accom- 
panied by belief, we have first images accompanied by 
belief and then sensations. Apart from differences as 
to the time-order and the accompanying feelings, the 
relation between image and sensation is closely similar 
in the two cases of memory and expectation ; it is a 
relation of similarity, with difference as to causal efficacy 
broadly, the image has the psychological but not the 
physical effects that the sensation would have. When 
an image accompanied by an expectation-belief is thus 
succeeded by a sensation which is the " meaning " of 
the image, we say that the expectation-belief has been 
verified. The experience of verification in this sense is 
exceedingly familiar ; it happens every time that accus- 
tomed activities have results that are not surprising, in 
eating and walking and talking and all our daily pursuits. 


But although the experience in question is common, 
it is not wholly easy to give a theoretical account of it. 
How do we know that the sensation resembles the previous 
image ? Does the image persist in presence of the sensa- 
tion, so that we can compare the two ? And even if 
some image does persist, how do we know that it is the 
previous image unchanged ? It does not seem as if this 
line of inquiry offered much hope of a successful issue. 
It is better, I think, to take a more external and causal 
view of the relation of expectation to expected occurrence. 
If the occurrence, when it comes, gives us the feeling 
of expectedness, and if the expectation, beforehand, 
enabled us to act in a way which proves appropriate to 
the occurrence, that must be held to constitute the 
maximum of verification. We have first an expectation, 
then a sensation with the feeling of expectedness related 
to memory of the expectation. This whole experience, 
when it occurs, may be defined as verification, and as 
constituting the truth of the expectation. Appropriate 
action, during the period of expectation, may be regarded 
as additional verification, but is not essential. The whole 
process may be illustrated by looking up a familiar 
quotation, finding it in the expected words, and in the 
expected part of the book. In this case we can strengthen 
the verification by writing down beforehand the words 
which we expect to find. 

I think all verification is ultimately of the above sort. 
We verify a scientific hypothesis indirectly, by deducing 
consequences as to the future, which subsequent experi- 
ence confirms. If somebody were to doubt whether 
Caesar had crossed the Rubicon, verification could only 
be obtained from the future. We could proceed to display 
manuscripts to our historical sceptic, in which it was 


said that Caesar had behaved in this way. We could 
advance arguments, verifiable by future experience, to 
prove the antiquity of the manuscript from its texture, 
colour, etc. t We could find inscriptions agreeing with 
the historian on other points, and tending to show his 
general accuracy. The causal laws which our arguments 
would assume could be verified by the future occurrence 
of events inferred by means of them. The existence 
and persistence of causal laws, it is true, must be regarded 
as a fortunate accident, and how long it will continue 
we cannot tell. Meanwhile verification remains often 
practically possible. And since it is sometimes possible, 
we can gradually discover what kinds of beliefs tend to 
be verified by experience, and what kinds tend to be 
falsified ; to the former kinds we give an increased degree 
of assent, to the latter kinds a diminished degree. The 
process is not absolute or infallible, but it has been found 
capable of sifting beliefs and building up science. It 
affords no theoretical refutation of the sceptic, whose 
position must remain logically unassailable ; but if com- 
plete scepticism is rejected, it gives the practical method 
by which the system of our beliefs grows gradually to- 
wards the unattainable ideal of impeccable knowledge. 

IV. I come now to the purely formal definition of 
the truth or falsehood of a belief. For this definition 
it is necessary first of all to consider the derivation of 
the objective reference of a proposition from the meanings 
of its component words or images. 

Just as a word has meaning, so a proposition has an 
objective reference. The objective reference of a pro- 
position is a function (in the mathematical sense) of the 
meanings of its component words. But the objective 
reference differs from the meaning of a word through 


the duality of truth and falsehood. You may believe 
the proposition " to-day is Tuesday " both when, in fact, 
to-day is Tuesday, and when to-day is not Tuesday. 
If to-day is not Tuesday, this fact is the objective of 
your belief that to-day is Tuesday. But obviously the 
relation of your belief to the fact is different in this case 
from what it is in the case when to-day is Tuesday. We 
may say, metaphorically, that when to-day is Tuesday, 
your belief that it is Tuesday points towards the fact, 
whereas when to-day is not Tuesday your belief points 
away from the fact. Thus the objective reference of a 
belief is not determined by the fact alone, but by the 
direction of the belief towards or away from the fact. 1 
If, on a Tuesday, one man believes that it is Tuesday 
while another believes that it is not Tuesday, their beliefs 
have the same objective, namely the fact that it is Tuesday, 
but the true belief points towards the fact while the 
false one points away from it. Thus, in order to define 
the reference of a proposition we have to take account 
not only of the objective, but also of the direction of 
pointing, towards the objective in the case of a true 
proposition and away from it in the case of a false one. 
This mode of stating the nature of the objective refer- 
ence of a proposition is necessitated by the circumstance 
that there are true and false propositions, but not true 
and false facts. If to-day is Tuesday, there is not a false 
objective " to-day is not Tuesday," which could be the 
objective of the false belief " to-day is not Tuesday." 
This is the reason why two beliefs which are each other's 
contradictories have the same objective. There is, how- 
ever, a practical inconvenience, namely that we cannot 

1 I owe this way of looking at the matter to my friend Ludwig 


determine the objective reference of a proposition, ac- 
cording to this definition, unless we know whether the 
proposition is true or false. To avoid this inconvenience, 
it is better to adopt a slightly different phraseology, 
and say : The " meaning " of the proposition " to-day 
is Tuesday " consists in pointing to the fact " to-day 
is Tuesday " if that is a fact, or away from the fact " to- 
day is not Tuesday " if that is a fact. The " meaning " 
of the proposition " to-day is not Tuesday " will be exactly 
the opposite. By this hypothetical form we are able to 
speak of the meaning of a proposition without knowing 
whether it is true or false. According to this definition, 
we know the meaning of a proposition when we know 
what would make it true and what would make it false, 
even if we do not know whether it is in fact true or false. 

The meaning of a proposition is derivative from the 
meanings of its constituent words. Propositions occur 
in pairs, distinguished (in simple cases) by the absence 
or presence of the word " not." Two such propositions 
have the same objective, but opposite meanings : when 
one is true, the other is false, and when one is false, the 
other is true. 

The purely formal definition of truth and falsehood 
offers little difficulty. What is required is a formal 
expression of the fact that a proposition is true when 
it points towards its objective, and false when it points 
away from it. In very simple cases we can give a very 
simple account of this : we can say that true propositions 
actually reseijible their objectives in a way in which 
false propositions do not. But for this purpose it is 
necessary to revert to image-propositions instead of 
word-propositions. Let us take again the illustration of 
a memory-image of a familiar room, and let us suppose 



that in the image the window is to the left of tfce door. 
If in fact the window is to the left of the door, there is 
a correspondence between the image and the objective ; 
there is the same relation between the window and the 
door as between the images of them. The image-memory 
consists of the image of the window to the left of the 
image of the door. When this is true, the very same 
relation relates the terms of the objective (namely the 
window and the door) as relates the images which mean 
them. In this case the correspondence which constitutes 
truth is very simple. 

In the case we have just been considering the ob- 
jective consists of two parts with a certain relation (that 
of left-to-right), and the proposition consists of images 
of these parts with the very same relation. The same 
proposition, if it were false, would have a less simple 
formal relation to its objective. If the image-proposition 
consists of an image of the window to the left of an image 
of the door, while in fact the window is not to the left 
of the door, the proposition does not result from the 
objective by the mere substitution of images for their 
prototypes. Thus in this unusually simple case we can 
say that a true proposition " corresponds " to its objective 
in a formal sense in which a false proposition does not. 
Perhaps it may be possible to modify this notion of formal 
correspondence in such a way as to be more widely ap- 
plicable, but if so, the modifications required will be 
by no means slight. The reasons for this must now be 

To begin with, the simple type of correspondence we 
have been exhibiting can hardly occur when words are 
substituted for images, because, in word-propositions, 
relations are usually expressed by words, which are 


not themselves relations. Take such a proposition as 
" Socrates precedes Plato/' Here the word " precedes " 
is just as solid as the words " Socrates " and " Plato " ; 
it means a relation, but is not a relation. Thus the 
objective which makes our proposition true consists of 
two terms with a relation between them, whereas our 
proposition consists of three terms with a relation of 
order between them. Of course, it would be perfectly 
possible, theoretically, to indicate a few chosen relations, 
not by words, but by relations between the other words. 
" Socrates-Plato " might be used to mean " Socrates 
precedes Plato " ; " Pla-Socrates-to " might be used to 
mean " Plato was born before Socrates and died after 
him " ; and so on. But the possibilities of such a method 
would be very limited. For aught I know, there may 
be languages that use it, but they are not among the 
languages with which I am acquainted. And in any 
case, in view of the multiplicity of relations that we 
wish to express, no language could advance far without 
words for relations. But as soon as we have words for 
relations, word-propositions have necessarily more terms 
than the facts to which they refer, and cannot therefore 
correspond so simply with their objectives as some image- 
propositions can. 

The consideration of negative propositions and negative 
facts introduces further complications. An image-pro- 
position is necessarily positive : we can image the windbw 
to the left of the door, or to the right of the door, but 
we can form no image of the bare negative " the window 
not to the left of the door." We can disbelieve the image- 
proposition expressed by " the window to the left of 
the door/ 1 and our disbelief will be true if the window 
is not to the left of the door. But we can form no image 


of the fact that the window is not to the left of the door. 
Attempts have often been made to deny such negative 
facts, but, for reasons which I have given elsewhere, 1 
I believe these attempts to be mistaken, and I shall 
assume that there are negative facts. 

Word-propositions, like image-propositions, are always 
positive facts. The fact that Socrates precedes Plato is 
symbolized in English by the fact that the word " pre- 
cedes " occurs between the words " Socrates " and 
" Plato/ 1 But we cannot symbolize the fact that Plato 
does not precede Socrates by not putting the word 
" precedes " between " Plato " and " Socrates/' A nega- 
tive fact is not sensible, and language, being intended 
for communication, has to be sensible. Therefore we 
symbolize the fact that Plato does not precede Socrates 
by putting the words " does not precede " between 
" Plato " and " Socrates/' We thus obtain a series 
of words which is just as positive a fact as the series 
" Socrates precedes Plato/' The propositions asserting 
negative facts are themselves positive facts ; they are 
merely different positive facts from those asserting 
positive facts. 

We have thus, as regards the opposition of positive 
and negative, three different sorts of duality, according 
as we are dealing with facts, image-propositions, or word- 
propositions. We have, namely : 

(1) Positive and negative facts ; 

(2) Image-propositions, which may be believed or 

disbelieved, but do not allow any duality of 
content corresponding to positive and negative 
facts ; 

1 Monist, January, 1919, p, 42 ft. 


(3) Word-propositions, which are always positive 
facts, but are of two kinds : one verified by 
a positive objective, the other by a negative 

Owing to these complications, the simplest type of 
correspondence is impossible when either negative facts 
or negative propositions are involved. 

Even when we confine ourselves to relations between 
two terms which are both imaged, it may be impossible 
to form an image-proposition in which the relation of 
the terms is represented by the same relation of. the 
images. Suppose we say " Caesar was 2,000 years before 
Foch," we express a certain temporal relation between 
Caesar and Foch ; but we cannot allow 2,000 years to 
elapse between our image of Caesar and our image of 
Foch. This is perhaps not a fair example, since " 2,000 
years before " is not a direct relation. But take a case 
where the relation is direct, say, " the sun is brighter 
than the moon." We can form visual images of sunshine 
and moonshine, and it may happen that our image of 
the sunshine is the brighter of the two, but this is by 
no means either necessary or sufficient. The act of 
comparison, implied in our judgment, is something more 
than the mere co-existence of two images, one of which 
is in fact brighteft than the other. It would take us too 
far from our main topic if we were to go into the question 
what actually ^ occurs when we make this judgment. 
Enough has been said to show that the correspondence 
between the belief and its objective is more complicated 
in this case than in that of the window to the left of the 
door, and this was all that had to be proved. 

In spite of these complications, the general nature of 


the formal correspondence which makes truth is clear 
from our instances. In the case of the simpler kind of 
propositions, namely those that I call " atomic " pro- 
positions, where there is only one word expressing a 
relation, the objective which would verify our proposition, 
assuming that the word " not " is absent, is obtained 
by replacing each word by what it means, the word 
meaning a relation being replaced by this relation 
among the meanings of the other words. For example, 
if the proposition is " Socrates precedes Plato," the 
objective which verifies it results from replacing the word 
" Socrates " by Socrates, the word " Plato " by Plato, and 
the word " precedes " by the relation of preceding between 
Socrates and Plato. If the result of this process is a 
fact, the proposition is true ; if not, it is false. When 
our proposition is " Socrates does not precede Plato," 
the conditions of truth and falsehood are exactly reversed. 
More complicated propositions can be dealt with on the 
same lines. In fact, the purely formal question, which 
has occupied us in this last section, offers no very for- 
midable difficulties. 

I do not believe that the above formal theory is untrue, 
but I do believe that it is inadequate. It does not, for 
example, throw any light upon our preference for true 
beliefs rather than false ones. This preference is only 
explicable by taking account of the causal efficacy of 
beliefs, and of the greater appropriateness of the responses 
resulting from true beliefs. But appropriateness depends 
upon purpose, and purpose thus becomes a vital part of 
theory of knowledge. 


ON the two subjects of the present lecture I have nothing 
original to say, and I am treating them only in order to 
complete the discussion of my main thesis, namely that 
all psychic phenomena are built up out of sensations 
and images alone. 

Emotions are traditionally regarded by psychologists 
as a separate class of mental occurrences : I am, of course, 
not concerned to deny the obvious fact that they have 
characteristics which make a special investigation of 
them necessary. What I am concerned with is the 
analysis of emotions. It is clear that an emotion is 
essentially complex, and we have to inquire whether it 
ever contains any non-physiological material not reducible 
to sensations and images and their relations. 

Although what specially concerns us is the analysis 
of emotions, we shall find that the more important topic 
is the physiological causation of emotions. This is a 
subject upon which much valuable and exceedingly in- 
teresting work has been done, whereas the bare analysis 
of emotions has proved somewhat barren. In view of 
the fact that we have defined perceptions, sensations, 
and images by their physiological causation, it is evident 
that our problem of the analysis of the emotions is 



bound up with the problem of their physiological 

Modern views on the causation of emotions begin 
with what is called the James-Lange theory. James 
states this view in the following terms (Psychology, vol. ii, 
p. 449) : 

" Our natural way of thinking about these coarser 
emotions, grief, fear, rage, love, is that the mental per- 
ception of some fact excites the mental affection called 
the emotion, and that this latter state of mind gives 
rise to, the bodily expression. My theory, on the contrary, 
is that the bodily changes follow directly the perception of 
the exciting fact, and that our feeling of the same changes 
as- they occur IS the emotion (James's italics). Common 
sense says : we lose our fortune, are sorry and weep ; 
we meet a bear, are frightened and run ; we are insulted 
by a rival, are angry and strike. The hypothesis here to 
be defended says that this order of sequence is incorrect, 
that the one mental state is not immediately induced 
by the other, that the bodily manifestations must first 
be interposed between, and that the more rational state- 
ment is that we feel sorry because we cry, angry because 
we strike, afraid because we tremble, and not that we 
cry, strike, or tremble, because we are sorry, angry, or 
fearful, as the case may be. Without the bodily states 
following on the perception, the latter would be purely 
cognitive in form, pale, colourless, destitute of emotional 
warmth/ 1 

Round this hypothesis a very voluminous literature 
has grown up. The history of its victory over earlier 
criticism, and its difficulties with the modern experimental 
work of Sherrington and Cannon, is well told by James 
R. Angell in an article called " A Reconsideration of 


James's Theory of Emotion in the Light of Recent Criti- 
cisms." J In this article Angell defends James's theoiy 
and to me though I speak with diffidence on a question 
as to which I have little competence it appears that 
his defence, is on the whole successful. 

Sherrington, by^ experiments on dogs, showed that 
many of the usual marks of emotion were present in 
their behaviour even when, by severing the spinal cord 
in the lower cervical region, the viscera were cut off from 
all communication with the brain except that existing 
.through certain cranial nerves. He mentions the various 
signs which " contributed to indicate the existence of 
an emotion as lively as the animal had ever shown us 
before the spinal operation had been made/' 2 He infers 
that the physiological condition of the viscera cannot 
be the cause of the emotion displayed under such cir- 
cumstances, and concludes : " We are forced back toward 
the likelihood that the visceral expression of emotion is 
secondary to the cerebral action occurring with the psychical 
state. . . . We may with James accept visceral and 
organic sensations and the memories and associations 
of them as contributory to primitive emotion, but we 
must regard them as re-enforcing rather than as initiating 
the psychosis. " a 

Angell suggests that the display of emotion in such 
cases may be due to past experience, generating habits 
which would require only the stimulation of cerebral 
reflex arcs. Rage and some forms of fear, however, may, 
he thinks, gain expression without the brain. Rage and 
fear have been especially studied by Cannon, whose work 
is of the greatest importance. His results are given in 

* Psychological Review, 1916. 
Quoted bv Anjrell. loc. cit. 


his book, Bodily Qhangts in Pain, Hunger, Fear and Rage 
(D. Appleton and Co., 1916). 

The most interesting part of Cannon's book consists 
in the investigation of the effects produced by secretion 
of adrenin. Adrenin is a substance secreted into the 
blood by the adrenal glands. These are among the 
ductless glands, the functions of which, both in physiology 
and in connection with the emotions, have only come to 
be known during recent years. Cannon found that pain, 
fear and rage occurred in circumstances which affected 
the supply of adrenin, and that an artificial injection 
of adrenin could, for example, produce all the symptoms 
of fear. He studied the effects of adrenin on various 
parts of the body ; he found that it causes the pupils to 
dilate, hairs to stand erect, bloodvessels to be constricted, 
and so on. These effects were still produced if the parts 
in question were removed from the body and kept alive 
artificially. 1 

Cannon's chief argument against James is, if I under- 
stand him rightly, that similar affections of the viscera 
may accompany dissimilar emotions, especially fear and 
rage. Various different emotions make us cry, and 
therefore it cannot be true to say, as James does, tha't 
we " feel sorry because we cry," since sometimes we cry 
when we feel glad. This argument, however, is by no 
means conclusive against James, because it cannot be 
shown that there are no visceral differences for different 
emotions, and indeed it is unlikely that this is the case. 

1 Cannon's work is not unconnected with that of Mosso, who 
maintains, as the result of much experimental work, that " the 
seat of the emotions lies in the sympathetic nervous system/ 1 
An account of the work of both these men will be found in God- 
dard's Psychology of the Normal and Sub-normal (Kegan Paul, 
1919)* chap, vii and Appendix. 


As Angell says (loc. cit.) : " Fear and joy may both cause 
cardiac palpitation, but in one case we find high tonus 
of the skeletal muscles, in the other case relaxation and 
the general sense of weakness." 

Angell's conclusion, after discussing the experiments of 
Sherrington and Cannon, is : "I would therefore submit 
that, so far as concerns the critical suggestions by these 
two psychologists, James's essential contentions are not 
materially affected." If it were necessary for me to take 
sides on this question, I should agree with this conclusion ; 
but I think my thesis as to the analysis of emotion can 
be maintained without coming to a probably premature 
conclusion upon the doubtful parts of the physiological 

According to our definitions, if James is right, an emotion 
may be regarded as involving a confused perception of 
the viscera concerned in its causation, while if Cannon 
and Sherrington are right, an emotion involves a confused 
perception of its external stimulus. This follows from 
what was said in Lecture VII. We there defined a per- 
ception as an appearance, however irregular, of one or 
more objects external to the brain. And in order to be 
an appearance of one or more objects, it is only necessary 
that the occurrence in question should be connected with 
them by a continuous chain, and should vary when they 
are varied sufficiently. Thus the question whether a 
mental occurrence can be called a perception turns upon 
the question whether anything can be inferred from it 
as to its causes outside the brain : if such inference is 
possible, the occurrence in question will come within our 
definition of a perception. And in that case, according 
to the definition in Lecture VIII, its non-mnemic elements 
will be sensations. Accordingly, whether emotions are 


caused by changes in the viscera or by sensible objects, 
they contain elements which are sensations according to 
our definition. 

An emotion in its entirety is, of course, something much 
more complex than a perception. An emotion is essentially 
a process, and it will be only what one may call a cross- 
section of the emotion that will be a perception, of a 
bodily condition according to James, or (in certain cases) 
of an external object according to his opponents. An 
emotion in its entirety contains dynamic elements, such 
as motor impulses, desires, pleasures and pains. Desires 
and pleasures and pains, according to the theory adopted 
in Lecture III, are characteristics of processes, not separate 
ingredients. An emotion rage, for example will be a 
certain kind of process, consisting of perceptions and 
(in general) bodily movements. The desires and pleasures 
and pains involved are properties of this process, not 
separate items in the stuff of which the emotion is composed. 
The dynamic elements in an emotion, if we are right in 
our analysis, contain, from our point of view, no ingre- 
dients beyond those contained in the processes considered 
in Lecture III. The ingredients of an emotion are only 
sensations and images and bodily movements succeeding 
each other according to a certain pattern. With this 
conclusion we may leave the emotions and pass to the 
consideration of the will. 

The first thing to be defined when we are dealing with 
Will is a voluntary movement. We have already defined 
vital movements, and we have maintained that, from a 
behaviourist standpoint, it is impossible to distinguish 
which among such movements are reflex and which 
voluntary. Nevertheless, there certainly is a distinction. 
When we decide in the morning that it is time to get up, 


our consequent movement is voluntary. The beating of 
the heart, on the other hand, is involuntary : we can 
neither cause it nor prevent it by any decision of our 
own, except indirectly, as e.g. by drugs. Breathing is 
intermediate between the two : we normally breathe 
without the help of the will, but we can alter or stop our 
breathing if we choose. 

James (Psychology, chap, xxvi) maintains that the 
only distinctive characteristic of a voluntary act is that 
it involves an idea of the movement to be performed, 
made up of memory-images of the kinaesthetic sensations 
which we had when the same movement occurred on some 
former occasion. He points out that, on this view, no 
movement can be made voluntarily unless it has previously 
occurred involuntarily. 1 

I see no reason to doubt the correctness of this view. 
We shall say, then, that movements which are accom- 
panied by kinaesthetic sensations tend to be caused by 
the images of those sensations, and when so caused are 
called voluntary. 

Volition, in the emphatic sense, involves something 
more than voluntary movement. The sort of case I 
am thinking of is decision after deliberation. Voluntary 
movements are a part of this, but not the whole. v There 
is, in addition to them, a judgment : " This is what I 
shall do " ; there is also a sensation of tension during 
doubt, followed by a different sensation at the moment 
of deciding. I see no reason whatever to suppose that 
there is any specifically new ingredient ; sensations and 
images, with their relations and causal laws, yield all 
that seems to be wanted for the analysis of the will, to- 
gether with the fact that kinaesthetic images tend to cause 
Psychology, vol. ii, pp. 492-3. 


the movements with which they are connected. Conflict 
of desires is of course essential in the causation of the 
emphatic kind of will : there will be for a time kinaesthetic 
images of incompatible movements, followed by the ex- 
clusive image of the movement which is said to be willed. 
Thus will seems to add no new irreducible ingredient to 
the analysis of the mind. 


Ax the end of our journey it is time to return to the 
question from which we set out, namely : What is it 
that characterizes mind as opposed to matter ? Or, 
to state the same question in other terms : How is 
psychology to be distinguished from physics ? The 
answer provisionally suggested at the outset of o.ur in- 
quiry was that psychology and physics are distinguished 
by the nature of their causal laws, not by their subject 
matter. At the same time we held that there is a certain 
subject matter, namely images, to which only psycho- 
logical causal laws are applicable ; this subject matter, 
therefore, we assigned exclusively to psychology. But we 
found no way of defining images except through their 
causation ; in their intrinsic character they appeared 
to have no universal mark by which they could be 
distinguished from sensations. 

In this last lecture I propose to pass in review various 
suggested methods of distinguishing mind from matter. 
I shall then briefly sketch the nature of that fundamental 
science which I believe to be the true metaphysic, in 
which mind and matter alike are seen to be constructed 
out of a neutral stuff, whose causal laws have no such 
duality as that of psychology, but form the basis upon 
which both physics and psychology are built. * 



In search for the definition of "mental phenomena/' 
let us begin with " consciousness," which is often 
thought to be the essence of mind. % In the first lecture 
I gave various arguments against the view that con- 
sciousness is fundamental, but I did not attempt to 
say what consciousness is. We must find a definition 
of it, if we are to feel secure in deciding that it is not 
fundamental. It is for the sake of the proof that it 
is not fundamental that we must now endeavour to 
decide what it is. 

" Consciousness," by those who regard it as fundamental, 
is taken to be a character diffused throughout our mental 
life, distinct from sensations and images, memories, 
feeliefs and desires, but present in all of them. 1 Dr. 
Henry Head, in an article which I quoted in Lecture 
III, distinguishing sensations from purely physiological 
occurrences, says : " Sensation, in the strict sense of 
the term, demands the existence of consciousness " 
(p. 184). This statement, at first sight, is one to which 
we feel inclined to assent, but I believe we are mistaken 
if we do so. Sensation is the sort of thing of which we 
may be conscious, but not a thing of which we must be 
conscious. We have been led, in the course of our 
inquiry, to admit unconscious beliefs and unconscious 
desires. There is, so far as I can see, no class of mental 
or other occurrences of which we are always conscious 
whenever they happen. *' 

Tbp first thing to notice is that consciousness must 
be of something. In view of this, I should define " con- 
sciousness " in terms of that relation of an image or 
a word to an object which we defined, "in Lecture XI, 
as " meaning." When a sensation is followed by an 
' Cf. Lecture VI, 


image which is a " copy " of it, I think it may be said 
that the existence of the image constitutes consciousness 
of the sensation, provided it is accompanied by that sort 
of belief which, when we reflect upon it, makes us feel 
that the image is a " sign " of something other than 
itself. This is the sort of belief which, in the case of 
memory, we expressed in the words "this occurred"; 
or which, in the case of a judgment of perception, makes 
us believe in qualities correlated with present sensations, 
as e.g., tactile and visual qualities are correlated. The 
addition of some element of belief seems required, since 
mere imagination does not involve consciousness of 
anything, and there can be no consciousness which 
is not of something. If images alone constituted 
consciousness of their prototypes, such imagination- 
images as in fact have prototypes would involve con- 
sciousness of them ; since this is not the case, an element 
of belief must be added to the images in defining 
consciousness. The belief must be of that sort that 
constitutes objective reference, past or present. An 
image, together with a belief of this sort concerning it, 
constitutes, according to our definition, consciousness 
of the prototype of the image. 

But when we pass from consciousness of sensations 
to consciousness of objects of perception, certain further 
points arise which demand an addition to our definition. 
A judgment of. perception, we may say, consists of a 
core of sensation, together with associated images, 
with belief in the present existence of an object to which 
sensation and images are referred in a way which is 
difficult to analyse. Perhaps we might say that the 
belief is not fundamentally in any present existence, 
but is of the nature of an expectation : for example, 



when we see an object, we expect certain sensations to 
result if we proceed to touch it. Perception, then, will 
consist of a present sensation together with expectations 
of future sensations. (This, of course, is a reflective 
analysis, not an account of the way perception appears 
to unchecked introspection.) But all such expectations 
are liable to be erroneous, since they are based upon 
correlations which are usual but not invariable. Any 
such correlation may mislead us in a particular case, 
for example, if we try to touch a reflection in a looking- 
glass under the impression that it is " real/' Since 
memory is fallible, a similar difficulty arises as regards 
.consciousness of past objects. It would seem odd to 
say that we can be " conscious " of a thing which does 
not or did not exist. The only way to avoid this awkward- 
ness is to add to our definition the proviso that the beliefs 
involved in consciousness must be true. 

In the second place, the question arises as to whether 
we can be conscious of images. If we apply our definition 
to this case, it seems to demand images of images. In 
order, for example, to be conscious of an image of a 
cat, we shall require, according to the letter of the defini- 
tion, an image which is a copy of our image of the cat, 
and has this image for its prototype. Now, it hardly 
seems probable, as a matter of observation, that there 
are images of images, as opposed to images of sensations. 
We may meet this difficulty in two ways, either by boldly 
denying consciousness of images, or by finding a sense 
in which, by means of a different accompanying belief, 
an image, instead of meaning its prototype, can mean 
another image of the same prototype. 

The first alternative, which denies consciousness of 
images, has already been discussed when we were 


dealing with Introspection in Lecture VI. We then 
decided that there must be, in some sense, consciousness 
of images. We are therefore left with the second suggested 
way of dealing with knowledge of images. According 
to this second hypothesis, there may be two images of 
the same prototype, such that one of them means the 
other, instead of meaning the prototype. It will be 
remembered that we defined meaning by association: 
a word or image means an object, we said, when it has 
the same associations as the object. But this definition 
must not be interpreted too absolutely : a word or image 
will not have all the same associations as the object which 
it means. The word " cat " may be associated with 
the word " mat," but it would not happen except by 
accident that a cat would be associated with a mat. 
And in like manner an image may have certain associa- 
tions which its prototype will not have, e.g. an associa- 
tion with the word " image/' When these associations 
are active, an image means an image, instead of mean- 
ing its prototype. If I have had images of a given proto- 
type many times, I can mean one of these, as opposed 
to the rest, by recollecting the time and place or any 
other distinctive association of that one occasion. This 
happens, for example, when a place recalls to us some 
thought we previously had in that place, so that we 
remember a thought as opposed to the occurrence to 
which it referred. Thus we may say that we think of 
an image A when we have a similar image B associated 
with recollections of circumstances connected with A, 
but not with its prototype or with other images of the 
same prototype. In this way we become aware of images 
without the need of any new store of mental contents, 
merely by the help of new associations. This theory, 


so far as I can see, solves the problems of introspective 
knowledge, without requiring heroic measures such as 
those proposed by Knight Dunlap, whose views we 
discussed in Lecture VI. 

According to what we have been saying, sensation 
itself is not an instance of consciousness, though the 
immediate memory by which it is apt to be succeeded 
is so. A sensation which is remembered becomes an 
object of consciousness as soon as it begins to be remem- 
bered, which will normally be almost immediately after 
its occurrence (if at all) ; but while it exists it is not an 
object of consciousness. If, however, it is part of a per- 
ception, say of some familiar person, we may say that 
the person perceived is an object of consciousness. For 
in this case the sensation is a sign of the perceived object 
in much the same way in which a memory-image is a 
sign of a remembered object. The essential practical 
function of " consciousness " and " thought " is that 
they enable us to act with reference to what is distant 
in time or space, even though it is not at present 
stimulating our senses. This reference to absent objects 
is possible through association and habit. Actual sen- 
sations, in themselves, are not cases of consciousness, 
because they do not bring in this reference to what is 
absent. But their connection with consciousness is 
very close, both through immediate memory, and through 
the correlations which turn sensations into perceptions. 

Enough has, I hope, been said to show that conscious- 
ness is far too complex and accidental to be taken as the 
fundamental characteristic of mind. We have seen that 
belief and images both enter into it. Belief itself, as 
we saw in an earlier lecture, is complex. Therefore, if 
any definition of mind is suggested by our analysis oi 


consciousness, images are /what would naturally suggest 
themselves. But since we found that images can only 
be defined causally, we cannot deal with this suggestion, 
except in connection with the difference between physical 
and psychological causal laws. 

I come next to those characteristics of mental pheno- 
mena which arise out of mnemic causation. The possi- 
bility of action with reference to what is not sensibly 
present is one of the things that might be held to 
characterize mind. Let us take first a very elementary 
example. Suppose you are in a familiar room at night, 
and suddenly the light goes out. You will be able to 
find your way to the door without much difficulty by 
means of the picture of the room which you have in 
your mind. In this case visual images serve, somewhat 
imperfectly it is true, the purpose which visual sensations 
would otherwise serve. The stimulus to the production 
of visual images is the desire to get out of the room, 
which, according to what we found in Lecture III, consists 
essentially of present sensations and motor impulses 
caused by them. Again, words heard or read enable 
you to act with reference to the matters about which 
they give information ; here, again, a present sensible 
stimulus, in virtue of habits formed in the past, enables 
you to act in a manner appropriate to an object which 
is not sensibly present. The whole essence of the practical 
efficiency of " thought " consists in sensitiveness to 
signs : the sensible presence of A, which is a sign of 
the present or future existence of B, enables us to act 
in a manner appropriate to B. Of this, words are the 
supreme example, since their effects as signs are prodigious, 
while their intrinsic interest as sensible occurrences on 
their own account is usually very slight. 


The operation of signs may or may not be accompanied 
by consciousness. If a sensible stimulus A calls up 
an image of B, and we then act with reference to B, we 
have what may be called consciousness of B. But habit 
may enable us to act in a manner appropriate to B as 
soon as A appears, without ever having an image of B. 
In that case, although A operates as a sign, it operates 
without the help of consciousness. Broadly speaking, 
a very familiar sign tends to operate directly in this manner, 
and the intervention of consciousness marks an imperfectly 
established habit. 

The power of acquiring experience, which characterizes 
men and animals, is an example of the general law that, 
in mnemic causation, the causal unit is not one event at 
one time, but two or more events at two or more times. 1 
A burnt child fears the fire, that is to say, the neighbourhood 
of fire has a different effect upon a child which has had 
the sensations of burning than upon one which has not. 
More correctly, the observed effect, when a child which 
has been burnt is put near a fire, has for its cause, not 
merely the neighbourhood of the fire, but this together 
"with the previous burning. The general formula, when 
an animal has acquired experience through some event 
A, is that, when B occurs at some future time, the animal 
to which A has happened acts differently from an animal 
which A has not happened. Thus A and B together, 
not either separately, must be regarded as the cause of 
the animal's behaviour, unless we take account of the 
effect which A has had in altering the animal's nervous 
tissue, which is a matter not patent to external observa- 
tion except under very special circumstances. With 
this possibility, we are brought back to causal laws, 
' Cf. Lecture IV. 


and to the suggestion that many things which seem 
essentially mental are really neural. Perhaps it is the 
nerves that acquire experience rather than the mind. 
If so, the possibility of acquiring experience cannot 
be used to define mind. 1 

Very similar considerations apply to memory, if taken 
as the essence of mind. A recollection is aroused by 
something which is happening now, but is different 
from the effect which the present occurrence would have 
produced if the recollected event had not occurred. 
This may be accounted for by the physical effect of the 
past event on the brain, making it a different instrument 
from that which would have resulted from a different 
experience. The causal peculiarities of memory may, 
therefore, have a physiological explanation. With every 
special class of mental phenomena this possibility meets 
us afresh. If psychology is to be a separate science 
at all, we must seek a wider ground for its separateness 
than any that we have been considering hitherto. 

We have found that " consciousness " is too narrow 
to characterize mental phenomena, and that mnemic 
causation is too wide. I come now to a characteristic 
which, though difficult to define, comes much nearer 
to what we require, namely subjectivity. 

Subjectivity, as a characteristic of mental phenomena, 
was considered in Lecture VII, in connection with the 
definition of perception. We there decided that those 
particulars which constitute the physical world can be 
collected into sets in two ways, one of which makes a 
bundle of all those particulars that are appearances 
of a given thing from different places, while the other 
makes a bundle of all those particulars which are appear- 

Cf. Lecture IV. 


ances of different things from a given place. A bundle 
of this latter sort, at a given time, is called a " perspective"; 
taken throughout a period of time, it is called a " bio- 
graphy." Subjectivity is the characteristic of perspectives 
and biographies, the characteristic of giving the view of 
the world from a certain place. We saw in Lecture VII 
that this characteristic involves none of the other 
characteristics that are commonly associated with mental 
phenomena, such as consciousness, experience and memory. 
We found in fact that it is exhibited by a photographic 
plate, and, strictly speaking, by any particular taken in 
conjunction with those which have the same " passive " 
place in the sense defined in Lecture VII. The par- 
ticulars forming one perspective are connected together 
primarily by simultaneity ; those forming one biography, 
primarily by the existence of direct time-relations between 
them. To these are to be added relations derivable from 
the laws of perspective. In all this we are clearly not 
in the region of psychology, as commonly understood ; 
yet we are also hardly in the region of physics. And 
the definition of perspectives and biographies, though 
it does not yet yield anything that would be commonly 
called " mental," is presupposed in mental phenomena, 
for example in mnemic causation : the causal unit in 
mnemic causation, which gives rise to Semon's engram, 
is the whole of one perspective not of any perspective, 
but of a perspective in a place where there is nervous 
tissue, or at any rate living tissue of some sort. Percep- 
tion also, as we saw, can only be defined in terms of 
perspectives. Thus the conception of subjectivity, i.e. 
of the " passive " place of a particular, thbugh not alone 
sufficient to define mind, is clearly an essential element 
in the definition. 


I have maintained throughout these lectures that 
the data of psychology do not differ in their intrinsic 
character from the data of physics. I have maintained 
that sensations are data for psychology and physics equally, 
while images, which may be in some sense exclusively psy- 
chological data, can only be distinguished from sensations 
by their correlations, not by what they are in themselves. 
It is now necessary, however, to examine the notion of 
a " datum/' and to obtain, if possible, a definition of 
this notion. 

The notion of " data " is familiar throughout science, 
and is usually treated by men of science as though it 
were perfectly clear. Psychologists, on the other hand, 
find great difficulty in the conception. " Data " are 
naturally defined in terms of theory of knowledge : they 
are those propositions of which the truth is known without 
demonstration, so that they may be used as premisses 
in proving other propositions. Further, when a proposi- 
tion which is a datum asserts the existence of something, 
we say that the something is a datum, as well as the 
proposition asserting its existence. Thus those objects 
of whose existence we become certain through perception 
are said to be data. 

There is some difficulty in connecting this epistemo- 
logical definition of " data " with our psychological 
analysis of knowledge ; but until such a connection has been 
effected, we have no right to use the conception " data." 

It is clear, in the first place, that there can be no datum 
apart from a belief. A sensation which merely comes 
and goes is not a datum ; it only becomes a datum when 
it is remembered. Similarly, in perception, we do not 
have a datum unless we have a judgment of perception. 
In the sense in which objects (as opposed to propositions) 


are data, it would seem natural to say that those objects 
of which we are conscious are data. But consciousness, 
as we have seen, is a complex notion, involving beliefs, 
as well as mnemic phenomena such as are required for 
perception and memory. It follows that no datum is 
theoretically indubitable, since no belief is infallible ; 
it follows also that every datum has a greater or less 
degree of vagueness, since there is always some vagueness 
in memory and the meaning of images. 

Data are not those things of which our consciousness 
is earliest in time. At every period of life, after we have 
become capable of thought, some of our beliefs are obtained 
by inference, while others are not. A belief may pass from 
either of these classes into the other, and may therefore 
become, or cease to be, a belief giving a datum. When, in 
what follows, I speak of data, I do not mean the things 
of which we feel sure before scientific study begins, but 
the things which, when a science is well advanced, appear 
as affording grounds for other parts of the science, with- 
out themselves being believed on any ground except 
observation. I assume, that is to say, a trained observer, 
with an analytic attention, knowing the sort of thing to 
look for, and the sort of thing that will be important. 
What he observes is, at the stage of science which he 
has reached, a datum for his science. It is just as 
sophisticated and elaborate as the theories which he 
bases upon it, since only trained habits and much practice 
enable a man to make the kind of observation that will 
be scientifically illuminating. Nevertheless, when once it 
has been observed, belief in it is not based on inference 
and reasoning, but merely upon its having been seen. 
In this way its logical status differs from that of the theories 
which are proved by its means. 


In any science other than psychology the datum is 
primarily a perception, in which only the sensational 
core is ultimately and theoretically a datum, though 
some such accretions as turn the sensation into a percep- 
tion are practically unavoidable. But if we postulate 
an ideal observer, he will be able to isolate the sensation, 
and treat this alone as datum. There is, therefore, 
an important sense in which we may say that, if we analyse 
as much as we ought, our data, outside psychology, consist 
of sensations, which include within themselves certain 
spatial and temporal relations. 

Applying this remark to physiology, we see that the 
nerves and brain as physical objects are not truly data ; 
they are to be replaced, in the ideal structure of science, 
by the sensations through which the physiologist is said 
to perceive them. The passage from these sensations 
to nerves and brain as physical objects belongs leally to 
the initial stage in the theory of physics, and ought to 
be placed in the reasoned part, not in the part supposed 
to be observed. To say we see the nerves is like saying 
we hear the nightingale ; both are convenient but in- 
accurate expressions. We hear a sound which we believe 
to be causally connected with the nightingale, and we 
see a sight which we believe to be causally connected 
with a nerve. But in each case it is only the sensatior 
that ought, in strictness, to be called a datum. Now,' 
sensations are certainly among the data of psychology. 
Therefore all the data of the physical sciences are also 
psychological data. It remains to inquire whether all 
the data of psychology are also data of physical science, 
and especially of physiology. 

If we have been right in our analysis of mind, the 
ultimate data of psychology are only sensations and 


images and their relations. Beliefs, desires, volitions, 
and so on, appeared to us to be complex phenomena 
consisting of sensations and images variously interrelated. 
Thus (apart from certain relations) the occurrences which 
seem most distinctively mental, and furthest removed 
from physics, are, like physical objects, constructed or 
inferred, not part of the original stock of data in the 
perfected science. From both ends, therefore, the differ- 
ence between physical and psychological data is dimi- 
nished. Is there ultimately no difference, or do images 
remain as irreducibly and exclusively psychological ? In 
view of the causal definition of the difference between 
jmages and sensations, this brings us to a new question, 
namely : Are the causal laws of psychology different from 
those of any other science, or are they really physiological ? 
Certain ambiguities must be removed before this ques- 
tion can be adequately discussed. 

First, there is the distinction between rough approxi- 
mate laws and such as appear to be precise and general. 
I shall return to the former presently ; it is the latter 
that I wish to discuss now. 

Majtter, as defined at the end of Lecture V, is a logical 
fiction, invented because it gives a convenient way of 
stating causal laws. Except in cases of perfect regularity 
in appearances (of which we can have no experience), 
the actual appearances of a piece of matter are not members 
of that ideal system of regular appearances which is 
defined as being the matter in question. But the matter 
is, after all, inferred from its appearances, which are 
used to verify physical laws. Thus, in so far as physics 
is an empirical and verifiable science, it* must assume or 
prove that the inference from appearances to matter is, 
in general, legitimate, and it must be able to tell us, more 


or less, what appearances to expect. It is through this 
question of verifiability and empirical applicability to 
experience that we are led to a theory of matter such as 
I advocate. From the consideration of this question it 
results that physics, in so far as it is an empirical science, 
not a logical phantasy, is concerned with particulars of 
just the same sort as those which psychology considers 
under the name of sensations. The causal laws of 
physics, so interpreted, differ from those of psychology 
only by the fact that they connect a particular with 
other appearances in the same piece of matter, rather 
than with other appearances in the same perspective. 
That is to say, they group together particulars having the 
same " active " place, while psychology groups together 
those having the same " passive " place. Some particulars, 
such as images, have no " active " place, and therefore 
belong exclusively to psychology. 

We can now understand the distinction between 
physics and psychology. The nerves and brain are 
matter : our visual sensations when we look at them may 
be, and I think are, members of the system constituting 
irregular appearances of this matter, but are not the 
whole of the system. Psychology is concerned, inter 
alia, with our sensations when we see a piece of matter, 
as opposed to the matter which we see. Assuming, as 
we must, that our sensations have physical causes, their 
causal laws are nevertheless radically different from the 
laws of physics, since the consideration of a single sensa- 
tion requires the breaking up of the group of which it is 
a member. When a sensation is used to verify physics, it 
is used merely as a sign of a certain material phenomenon, 
i.e. of a group of particulars of which it is a member. 
But when it is studied by psychology, it is taken away 


from that group and put into quite a different context, 
where it causes images or voluntary movements. It 
is primarily this different grouping that is characteristic 
of psychology as opposed to all the physical sciences, in- 
cluding physiology ; a secondary difference is that images, 
which belong to psychology, are not easily to be included 
among the aspects which constitute a physical thing or 
piece of matter. 

There remaiilfe, however, an important question, 
namely : Are mental events causally dependent upon 
physical events in a sense in which the converse dependence 
does not hold ? Before we can discuss the answer to 
this question, we must first be clear as to what our 
question means. 

When, given A, it is possible to infer B, but given 
B, it is not possible to infer A, we say that B is dependent 
upon A in a sense in which A is not dependent upon 
B. Stated in logical terms, this amounts to saying 
that, when we know a many-one relation of A to B, B 
is dependent upon A in respect of this relation. If the 
relation is a causal law, we say that B is causally dependent 
upon A. The illustration that chiefly concerns us is the 
system of appearances of a physical object. We can, 
broadly speaking, infer distant appearances from near 
ones, but not vice versa. All men look alike when they 
are a mile away, hence when we see a man a mile off 
we cannot tell what he will look like when he is only a 
yard away. But when we see him a yard away, we 
can tell what he will look like a mile away. Thus the 
nearer view gives us more valuable information, and 
the distant view is causally dependent upon it in a sense 
in whicji it is not causally dependent upon the distant 


It is this greater causal potency of the near appearance 
that leads physics to state its causal laws in terms of 
that system of regular appearances to which the nearest 
appearances increasingly approximate, and that makes 
it value information derived from the microscope or 
telescope. It is clear that our sensations, considered 
as irregular appearances of physical objects, share the 
causal dependence belonging to comparatively distant 
appearances ; therefore in our sensational life we are 
in causal dependence upon physical laws. 

This, however, is not the most important or interesting 
part of our question. It is the causation of images that 
is the vital problem. We have seen that they are 
subject to mnenic causation, and that mnenic causation 
may be reducible to ordinary physical causation in nervous 
tissue. This is the question upon which our attitude 
must turn towards what may be called materialism. 
One sense of materialism is the view that all mental 
phenomena are causally dependent upon physical phe- 
nomena in the above-defined sense of causal dependence. 
Whether this is the case or not, I do not profess to know. 
The question seems to me the same as the question 
whether mnemic causation is ultimate, which we considered 
without deciding in Lecture IV. But I think the bulk 
of the evidence points to the materialistic answer as 
the more probable. 

In considering the causal laws of psychology, the 
distinction between rough generalizations and exact laws 
is important. There are many rough generalizations 
in psychology, not only of the sort by which we goverr 
our ordinary behaviour to each other, but also of a mon 
nearly scientific kind. Habit and association belong 
among such laws. I will give an illustration of the kinc 


of law that can be obtained. Suppose a person has 
frequently experienced A and B in close temporal con- 
tiguity, an association will be established, so that A, 
or an image of A, tends to cause an image of B. The 
question arises : will the association work in either direc- 
tion, or only from the one which has occurred earlier to 
the one which has occurred later ? In an article by Mr. 
Wohlgemuth, called " The Direction of Associations " 
(British Journal of Psychology, vol. v, part iv, March, 
1913), it is claimed to be proved by experiment that, 
in so far as motor memory (i.e. memory of movements) 
is concerned, association works only from earlier to 
later, while in visual and auditory memory this is not 
the case, but the later of two neighbouring experiences 
may recall the earlier as well as the earlier the later. 
It is suggested that motor memory is physiological, 
while visual and auditory memory are more truly 
psychological. But that is not the point which con- 
cerns us in the illustration. The point which concerns 
us is that a law of association, established by purely 
psychological observation, is a purely psychological law, 
and may serve as a sample of what is possible in the way 
of discovering such laws. It is, however, still no more 
than a rough generalization, a statistical average. It 
cannot tell us what will result from a given cause on a 
given occasion. It is a law of tendency, not a precise 
and invariable law such as those of physics aim at being. 
If we wish to pass from the law of habit, stated as 
a tendency or average, to something more precise and 
invariable, we seem driven to the nervous system. We 
can more or less guess how an occurrence produces a 
change in the brain, and how its repetition gradually 
produces something analogous to the channel of a river, 


along which currents flow more easily than in neighbour- 
ing paths. We can perceive that in this way, if we had 
more knowledge, the tendency to habit through repetition 
might be replaced by a precise account of the effect of 
each occurrence in bringing about a modification of the 
sort from which habit would ultimately result. It is 
such considerations that make students of psycho- 
physiology materialistic in their methods, whatever they 
may be in their metaphysics. There are, of course, ex- 
ceptions, such as Professor J. S. Haldane, 1 who maintains 
that it is theoretically impossible to obtain physiological 
explanations of psychical phenomena, or physical explana- 
tions of physiological phenomena. But I think the bulk 
of expert opinion, in practice, is on the other side. 

The question whether it is possible to obtain precise 
causal laws in which the causes are psychological, not 
material, is one of detailed investigation. I have done 
what I could to make clear the nature of the question, 
but I do not believe that it is possible as yet to answer 
it with any confidence. It seems to be by no means an 
insoluble question, and we may hope that science will 
be able to produce sufficient grounds for regarding one 
answer as much more probable than the other. But for 
the moment I do not see how we can come to a decision. 

I think, however, on grounds of the theory of matter 
explained in Lectures V and VII, that an ultimate scientific 
account of what goes on in the world, if it were ascertain- 
able, would resemble psychology rather than physics 
in what we found to be the decisive difference between 
them. I think, that is to say, that such an account 
would not be content to speak, even formally, as though 

* See his book, The New Physiology and Other Addresses (Charles 
Griffin # Co., 1919). 


matter, which is a logical fiction, were the ultimate 
reality. I think that, if our scientific knowledge werp 
adequate to the task, which it neither is nor is likely to 
become, it would exhibit the laws of correlation of the 
particulars constituting a momentary condition of a 
material unit, and would state the causal laws x of the 
world in terms of these particulars, not in terms of matter. 
Causal laws so stated would, I believe, be a] p'icable 
to psychology and physics equally ; the science in 
which they were stated would succeed in achieving 
what metaphysics has vainly attempted, namely a 
unified account of what really happens, wholly true 
even if not the whole of truth, and free from all con- 
venient fictions or unwarrantable assumptions of meta- 
physical entities. A causal law applicable to particulars 
would count as a law of physics if it could be stated 
in terms of those fictitious systems of regular appear- 
ances which are matter ; if this were not the case, 
it would count as a law of psychology if one of the 
particulars were a sensation or an image, i.e. were 
subject to mnemic causation. I believe that the realiza- 
tion of the complexity of a material unit, and its analysis 
into constituents analogous to sensations, is of the utmost 
importance to philosophy, and vital for any understand- 
ing of the relations between mind and matter, between 
our perceptions and the world which they perceive. It 
is in this direction, I am convinced, that we must look 
for the solution of many ancient perplexities. 

It is probable that the whole science of mental 
occurrences, especially where its initial definitions are 

* In a perfected science, causal laws will take the form of differen- 
tial equations or of finite-difference equations, if the theory of 
quanta should prove correct, 


concerned, could be simplified by the development of 
the fundamental unifying science in which the causal 
laws of particulars are sought, rather than the causal 
laws of those systems of particulars that constitute the 
material units of physics. This fundamental science 
would cause physics to become derivative, in the sort 
of way in which theories of the constitution of the atom 
make chemistry derivative from physics ; it would also 
cause psychology to appear less singular and isolated 
among sciences. If we are right in this, it is a wrong 
philosophy of matter which has caused many of the 
difficulties in the philosophy of mind difficulties which 
a right philosophy of matter would cause to disappear. 

The conclusions at which we have arrived may be 
summed up as follows : 

I. Physics and psychology are not distinguished by 
their material. Mind and matter alike are logical 
constructions ; the particulars out of which they are 
constructed, or from which they are inferred, have various 
relations, some of which are studied by physics, others by 
psychology. Broadly speaking, physics group particulars 
by their active places, psychology by their passive places. 

II. The two most essential characteristics of the 
causal laws which would naturally be called psychological 
are subjectivity and mncmic causation ; these are not 
unconnected, since the causal unit in mnemic causation 
is the group of particulars having a given passive place 
at a given time, and it is by this manner of grouping 
that subjectivity is defined. 

III. Habit, memory and thought are all develop- 
ments of mnemic causation. It is probable, though not 
certain, that mnemic causation is derivative from 
ordinary physical causation in nervous (and other) tissue. 


IV. Consciousness is a complex and far from universal 
characteristic of mental phenomena. 

V. Mind is a matter of degree, chiefly exemplified 
in number and complexity of habits. 

VI. All our data, both in physics and psychology, 
are subject to psychological causal laws ; but physical 
causal laws, at least in traditional physics, can only be 
stated in terms of matter, which is both inferred and 
constructed, never a datum. In this respect psychology 
is nearer to what actually exists. 


Accuracy, 2, 180, 255 
Akoluthic sensations, 162, 175 
Appropriateness, 255, 259 
Assent, 250 

Bain, 247 

Behaviourism, 157, 160, 172, 201, 

254, 257 
Belief, chap. xii. 
Bennett, 73 

Bergson, 36, 55, 166, 172, 179, 180 
Berkeley, 214, 208 
Buhler, 223 
Butler, 167 

Cannon, 280 
Causal efficacy, 244 
Coherence, 262, 266 
Consciousness, chap, i., 244, 288,295 

Darwin^ 90 

Definition of a piece of matter, 107 

Desire and Feeling, chap. iii. 

Dewey, 26 

Dispositions, 246 

Donne, 73 

Drever, 55 

Dunlap, no, 120 

Emotions and Will, chap. xiv. 
Expectation, 176, 250 

Fabre, 55 

Feeling and Desire, chap. iv. 


of familiarity, 161, 163, 168 

of pastness, 162 

of reality, 186 
Freud, 33, 39 

Galton, 153 

General Ideas and Thought, chap. 

Goddard, 282 

Habit and Instinct, chap. ii. 

Haldane, 90 

Hart, 34 

Head, 70, 288 

Hegel, 1 80, 266 

Herbart, 28 

Hobbes, 190 

Hobhouse, 54 

Holt, 25 

Hume, 155, 158, 208, 214 

Image-propositions, 248 
Images, 290 

Imagination images, 202, 249 
Instinct and Habit, chap. ii. 
Instinctive behaviour, 49 
Instrument as a " measure," 183 
Introspection, chap. vi. 

James, 22, 44, 82, in, 174, 248, 

252, 280, 285 
Joachim, 266 
Jung, 33, 

Kant, 109 

of the future, 164 

of the past, 164 

Lange, 280 
Language, 190 
Lloyd Morgan, 28, 49 
Locke, 214 
Lossky, 261 




Mach, 22 

Meaning, 179 

Meinong, 16, 164, 262 

Memory, 12, chap, ix., 249 

Memory-images, 174, 178, 185, 207 

Mental Phenomena, chap. xv. 

Messer, 223 

Mnemic causation, 209 

Morton Price, 33 

Mosso, 282 

Particulars, 193 
Perception, 12, chap, vii., 265 
Perry, 25 
Plato, 213 

Psychological and Physical Causal 
La\vs, chap. v. 

Quantum theory, 94 

Recognition, 168, 172 
Reflex movements, 244 
Reliability of an instrument, 183 
Ribot, 184, 198, 222 
Rousseau, 190 

Schiller, 26 
Sell-evidence, 262 

Semon, 66, 78, 83, 90, 165, 175, 

207, 219 

Sensation, 157, 174 
Sensations and Images, chap. viii. 
Sensitiveness, 260 
Slicrrington, 280 
Specious present, 174 
Speech, i 90 
Spinoza, 248 
Stout, in 

Thorndike, 51, 72, 80, 226 

Titchener, 223 

Truth and Falsehood, chap. xiii. 

Vagueness, 180 
Verifiability, 254, 268 
Voluntary movements, 244, 284 

Watson, 26, 52, 197, 199, 203, 223 

Watt, 223 

Will, chap, xiv., 244 

Wittgenstein, 272 

Wohlgemuth, Oy, 70, 159, 205, 


Words and Meaning, chap. x. 
Wrinch, 176 
Wundt, 196, 224 

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exaggerated ... it seems to me quite excellent." 

Elements of Constructive 


( Camb .). HON. LL.D. (Glasg.) 

Emeritus Professor of Logic and Philosophy in University College, Cardiff; 

formerly Fellow of Trinity College, Cambridge 

Demy %vo. Second Impressitn 

"The book is sufficient. In its pages is all that the educated man 
needs to know or is likely to care to know. The arrangement is 
methodical ; the style is crisp and conclusive." Expository Times. 

The Rational Good : A Study 
in the Logic of Practice 

By L. T. HOBHOUSE, D.Lrrr., LL.D. 
Demy 8ve. 8/. 6d. net. 

" Professor Hobhouse has rare powers of analysis and insight. . . . No 
living writer has applied more successfully the evolutionary method to 
ethics." Manchester Guardian. 

Elements of Social Justice 

By L. T. HOBHOUSE, D.Lrrr., LL.D. 

Martin White Professor of Sociology in the University of London 
Demy %vo. . ios. 6d. net. 

"He combines profound penetration with wide range and catholic 
sympathies. Unlike so many philosophical books, this one is written in 
English that is good to read. Manchester Guardian.